专题强化训练3-1答案
人教版五年级数学下册第3单元强化训练附答案(1) (1)
人教版五年级数学下册第3单元强化训练(1)考点梳理＋易错总结＋单元综合测评满分：100分试卷整洁分：2分题号一二三四五六七八总分附加题得分（74分）1长方体、正方体的认识一、细心填写。
(每空1分，共15分)1．长方体有( )个面，( )个顶点，( )条棱，相对的两个面( )。
2．正方体有( )个面，每个面都是( )形，面积都( )。
3．长方体相交于一个顶点的三条棱的长度分别叫做它的( )、( )、( )。
4．常见的牙膏盒的形状是( )体，魔方的形状是( )体。
5．一个长方体的长1.5dm，宽1.2dm，高1dm，它的棱长总和是( )dm。
6．用一根长1米的铁丝焊接成一个长方体框架，它的底面周长是30厘米，高是( )厘米。
7．把两个棱长是2 cm的正方体拼成一个长方体，这个长方体的棱长总和是( )cm。
二、精挑细选。
(将正确答案的序号填在括号里)(8分)1．一个正方体的棱长总和是84 cm，它的棱长是( )cm。
A．21 B．14 C．72．用棱长1 cm的小正方体拼成一个稍大的正方体，至少要用( )个小正方体。
A．4 B．8 C．163．用一根长52 cm的铁丝，正好焊成一个长6 cm，宽4 cm，高( )的长方体框架。
A．2 cm B．3 cm C．4 cm4．两个相同的长方体木块，长10 cm，宽5 cm，高2 cm。
现在把这两个长方体(如下图)拼成一个大长方体。
大长方体的棱长和比这两个小长方体棱长总和少( )。
A．60 cm B．48 cm C．28 cm2长方体和正方体的表面积三、正方体的6个面分别写着1、2、3、4、5、6六个数字，与1、3、4相对的面分别写着什么数字？(9分)1→( )3→( )4→( )四、认真填写。
(每空2分，共10分)1．用铁丝扎一个长方体框架，求铁丝的长就是求长方体的( )；在这个铁架上蒙白纸，求需要多少白纸就是求长方体的( )。
2．一个长方体的长是12 cm，宽是8 cm，高是4 cm，这个长方体的六个面中最大面的面积是( )cm2，最小面的面积是( )cm2。
阅读专题强化训练2020-2021学年人教版八年级英语下学期期末考前必备(含答案)
阅读理解专题强化训练——人教版八年级下册期末考前必备【练习1】It’s important for us to keep healthy. But in fact, many people have health problems. Many people fall ill and many children become heavier.As we grow older, we experience many life changes, such as job changes, children leaving home and physical (身体的) changes. How we grow from these changes is the key to staying healthy.These ways can help us keep our physical and emotional (情绪的) health. First, we must keep away from smoking and drinking. Second, we should do exercise every day. We can walk to school instead of taking a bus or a car. Third, we shouldn’t eat too much fast food. We can eat more fruit and vegetables.Many studies show that people always feel better when they’re with friends than when they’re alone. So be sure to make some friends.Staying healthy is important at any age and that doesn’t change just because we have a few more white hairs.1. The writer mainly tells us ______ has something to do with our health.A. what we likeB. what we experienceC. how we go to schoolD. how we look2. From the second paragraph, we can know if we want to keep healthy we must learn to face ______.A. life changesB. health problemsC. food problemsD. exercise problems3. The writer tells us ______ are the ways to stay healthy in the third paragraph.A. eating more fruit and doing exerciseB. stopping smoking and drinkingC. exercise and good eating habitsD. A, B and C4. If we want to feel better, we can______.A. see doctors oftenB. exercise more and drink lessC. keep our life fullD. make more friends5. The passage mainly tells us______.A. how to keep physical and emotional healthB. three ways to stay thinC. how to feel wellD. staying healthy is very important1-2 DBADD【练习2】Medical experts say most Americans do not get enough sleep. They say more Americans need to take a nap—that is to rest for a short period in the middle of the day. They give people advice to sleep lightly before continuing with other activities. The experts say naps might improve health by reducing pressure.Some European and Latin American companies have supported the idea of napping for many years. They ask people to leave work, go home and have a nap before returning. In the United States, some companies let workers rest simply in their offices. They believe this can help workers make fewer mistakes and also increase the amount of work that a person can do.Sleep experts say it is likely that people make more mistakes at work than at other times. They say people should not carry out important tasks when they feel sleepy. And they say the best thing to do is to take a nap. About twenty minutes of rest is all you need. Experts say this provides extra energy and can increase your effects until the end of the day. But experts said that a nap should last no more than twenty to thirty minutes. A longer nap will put the body into deep sleep and waking up will be difficult.1. This passage is probably taken from ___________.A. a story bookB. a posterC. a science fictionD. medical magazine2. What’s the best way to increase workers’ effects?A. Talking with friends.B. Doing relaxing exercises.C. Laughing, smiling and crying.D. Having a rest for twenty or thirty minutes.3. What will happen to the workers if they keep on working without any rest?A. They will get a lot of money.B. They will fail in their jobs and even cause a lot of trouble.C. They will live a happy life in the future.D. They will feel better after finishing everyday jobs.4. The meaning of the underlined word “reducing” in the first paragraph is “______A. 加大B. 缓解C. 产生D. 制造5. The passage mainly talks about____________.A. taking a nap during the dayB. the disadvantages of taking a napC. Americans who don’t have a nap during the weekendsD. the advantages of deep sleep1-5 ADDBB【练习3】Many of us don’t pay much attention to the importance of eye care. It is said that if you take care of your body, then you can surely be healthy. That is why our eyes should be given a lot of care. Natural eye care should be put in a number one place.There are several causes leading to poor eyesight like not enough food, genes (基因) and aging (老化). Televisions, computers and reading are also the causes of having poor eyesight. If you happen to work in front of the computer, it is best to take a break every once in a while.Something dirty can cause redness and they will make you feel uncomfortable. It is bad for your eyes too. If this happens, the best way is to clean your eyes by using cold water. You must also try your best to protect your eyes from harmful things. For example, sunglasses are not just for fashion but they can also serve as a great way to protect your eyesight from UVrays.Eating healthy foods will do good to your eyesight. Remember that vitamins A, C and E are good for eyes. Try to eat food groups that have these vitamins. And you should do eye exercises because exercise protects your eyesight too. If a person exercises regularly (定期地) and eats the right kind of food, his eyes will stay in good condition for a long time.All above are natural ways of eye care that help us keep healthy eyes. Being happy all the time can be helpful to a person’s eyesight, too. In a word, eye care is very important, no matter how old a person is.1. ___________ is the most important way to protect our eyes.A. Taking medicineB. Natural eye careC. Seeing the doctorD. Being happy all the time2. What should you do if you have to work in front of the computer?A. Having a rest after working for a while.B. Eat healthy foods.C. Clean the eyes by using cold water.D. Wear a pair of sunglasses.3. What do the underlined words “UV rays” mean?A. 闪电B. 沙尘C. 紫外线D. 超声波4. Which is the best title of the passage?A. Ways of Eye ExercisesB. Ways of Eye CareC. Ways of Being HappyD. Ways of Being Healthy1-4 BACB【练习4】Early to bed, early to rise, makes a man healthy, wealthy and wise. This is an old English saying. Have you heard of it before? It means that we must go to bed early and get up early in the morning. Then we shall be healthy. We shall also be rich (wealthy) and clever (wise).This is true. The body must have enough sleep to be healthy. Children of young age should have ten hours’ sleep every night. Children who do not have enough sleep cannot do their work very well. They will not be wise and they may not become wealthy!The body also needs exercise. Walking, running, jumping, swimming and playing games are all exercise. Exercise keeps the body strong. Exercise also helps the blood (血液) to move around inside the body. This is very important. Our blood takes food to all parts of our body. The head also needs blood. Exercise helps us to think better!1. If we get up early and go to bed early, we’ll ______ .A. have enough exerciseB.be healthyC. think betterD. have strong blood2. If a child doesn’t have 10 hours’ sleep, maybe he _____ .A. becomes wiseB. won’t do well in his workC. goes to school in timeD. has enough sleep3. A person needs exercise because _______ .A. it makes him healthyB. he has a lot of homework to doC. he is strong enoughD. he does exercise4. Exercise makes the ______ move quickly and smoothly(流畅).A. BodyB. bloodC. childrenD. head5. Which of the following if Not TRUE?A. Exercise does good to a person’s headB. A student should have 10 hours’ sleepC. It’s good for you to get up early and go to bed early.D. If you have enough blood, you’ll be wise.1-5 BBABD【练习5】Running is becoming popular these days. Many of us run for health. Doctors say many health problems come from these bad habits：eating and drinking too much, smoking and not taking enough exercise. Doctors tell us, “Eat and drink less, don’t smoke, and exercise more.”Running is a good form of exercise because it helps build a strong heart. It also helps most people lose weight. One 68-year-old woman runs three times a week. “I love to eat,” she says. She runs to lose weight.Running is good for health in other ways, too. Many runners say running keeps colds and other small health problems away. “Running is my doctor,” says one man.Running can also help people to relax. So today men and women of all ages enjoy running.1. Many people enjoy running because they want to___________.A. eat muchB. keep healthyC. run fastD. waste time2. Doctors tell us _____________.A. not to smokeB. not to exerciseC. to drink muchD. to eat much3. The underlined word means “_______” in Chinese.A. 疾病B. 体重C. 速度D. 健康4. The third paragraph shows_____________.A. running helps people to relaxB. people who like running have many health problemsC. running helps build a strong heartD. people who like running have fewer health problems5. The writer mainly tells us ___________.A. how to runB. how to lose weightC. running is a good way to keep healthyD. running is better than doctors1-5 BABDC【练习6】Mary Jo Ray turned 113 in May, 2008. She was the twelfth oldest person in the world. Ray was one of the few people who lived to more than (多于) 110 years old. We often call them. “She often drinks milk. She hardly gets angry with others and is always happy. So she is in good health. I think her reason for long life is drinking milk every day and trying to be happy,” said her granddaughter (孙女).Her doctor, Dr. Perls, said another reason for Ray’s long life is her genes (基因). She got them from her parents. He said, “These genes can keep you in good health and let you live longer. People can usually live to about 80 years old. Those with the right genes can live to more than 100 years. They also pass those genes to their children. So if a person’s parents live long, he or she will probably live long, too.” Dr. Perls also said, “You may not have those genes. But if you don’t smoke, don’t drink too much, and do exercise or do other things to relax, you still can live long.”1. Mary Jo Ray was the ______ oldest person in the world in 2008.A.11thB.12thC.13thD.14th2. The underlined word “centenarian” means “_______” in Chinese.A. 健康的人B. 聪明的人C. 杰出的人D.百岁的人3. From the passage, we can learn that Mary Jo Ray ___________.A. hardly drinks milkB.is never happyC. has the genes for long lifeD. often gets angry with others4. Mary Jo Ray’s father probably lived a(n) _______ life.A. LongB. hardC. shortD. easy5. The passage is mainly about _______.A. the family of Mary Jo RayB. how people can live betterC. why Mary Jo Ray lives longD. Mary Jo Ray’s doctor1-5 BDCAC【练习7】Coffee has played an important role in people’s lives for thousands of years, and today coffee is grown and enjoyed worldwide; it is still one of the favorite drinks in the world. Many people in the world begin their busy day by drinking a cup of coffee or several cups of coffee. They have always said that a cup of coffee in the morning helps them begin their day in the right way.Do you know what in the coffee makes our bodies and brains (头脑) active? It is caffeine (咖啡因). Caffeine may increase a person’s mental and physical abilities (精力和体力). For example, two cups of coffee will make you breathe (呼吸) faster and augment body temperature. All this makes your heart beat faster, and doctors warn that this may be a little dangerous.Caffeine is found in tea, coffee, chocolate and some other foods. A little caffeine is probably not harmful. But too much caffeine can make people nervous and sleepless.1.“A cup of coffee in the morning helps them begin their day in the right way.” What does it mean?A. A cup of coffee helps them do the right job.B. A cup of coffee helps them act in the right way the whole morning.C. A cup of coffee makes their work more interesting.D. A cup of coffee makes them full of spirit for the work the whole day.2. The underlined word “augment” means __________.A. make moreB. drinkC. stopD. make less3. Caffeine is found in __________.A. tea and waterB. chocolate, meat and some other foodsC. coffee and creamD. coffee, tea, chocolate and some other foods4. From the passage, we may know drinking coffee late at night might _________.A. give you a headacheB. make you fall asleepC. keep you awakeD. may be dangerous5. Which of the following is NOT true?A. People have used coffee since thousands of years ago.B. Caffeine does no harm to our body.C. Two cups of coffee will make you breathe faster and increase body temperature.D. Caffeine may increase man’s mental and physical abilities.1-5 DADCB【练习8】“ Early to bed and early to rise make a man healthy , wealthy and wise.” This is an old English saying. It means that when we go to bed early, we can get up early the next morning. Then we will become healthy. We will also become rich and clever.This is true. To keep healthy, we must have enough sleep. Experts (专家) say that adults should get seven to eight hours of sleep a night. Teenagers need nine to ten hours. And school-aged children may need more than ten hours of sleep. Children who do not have enough sleep can’t do their work very well. They won’t be wise and they may not become wealthy！We also need exercise. Walking, running, swimming and playing games are all exercise. Exercise keeps us strong. It also helps the blood to move around the body. This is very important. Our blood takes the nutrition (营养) from food to all parts of our body.The head also needs blood. So exercise that moves the blood to our head helps us think better！1. If we get up early and go to bed early, we’ll .A. become weakB. have more timeC. be healthyD. have more work to do2. Who needs most hours of sleep to keep healthy？A. Adults.B. Teenagers.C. Experts.D. School-aged children.3. A child when he does not have enough sleep.A. can’t study wellB. will be wiseC. will be wealthyD. will be active in class4. A person needs exercise because .A. he is not strong enoughB. it helps make him healthyC. he has a lot of homework to doD. it can bring him much blood5. Which of the following is NOT true？A. Exercise helps the blood to move.B. Exercise is good for a person’s head.C. If we have enough blood, we’ll be wise.D. It’s good for us to get up early and go to bed early.1-5 C D A B C【练习9】Hobbies are very important to a person. Without having any hobby, life won’t be as colorful as it should be.I have a number of hobbies , such as collecting stamps, playing musical instruments (乐器), reading, and doing sport activities. When I am free,1 will spend time on my hobbies. When I am in a blue mood (情绪低落), I will also do my hobbies to cheer myself up.Hobbies can help us improve our moods. Many hobbies require you to put your heart in them. For example , when you play a musical instrument , you have to practice over and over in order to perform (表演) good music. After a period (一段时期) if you still enjoy it ,gradually (逐渐地) it will become a hobby of yours. But remember ,a hobby is like gold (金子) under the ground; no hobby will come to your unless (除非) you dig it out yourself. If you can treat study as one of your hobbies, learning will be more enjoyable. I hope all of you can find your own hobbies and also have fun from them.1. What makes our life colorful？A. Playing musical instruments.B. Collecting stamps.C. The blue mood.D. The hobbies.2. Hobbies sometimes can make a personA. in a blue moodB. find gold under the groundC. cheer himself/herself upD. perform good3. If we want to have a hobby, we mustA. practice over and over.B. put our heart in it.C. spend a lot of time on it.D. all the above.4. How can we make our study enjoyable？A. Practice over and over.B. Improve our moods.C. Treat our study as a hobby.D. We shouldn’t have hobbies5. Which of these is WRONG?A. Hobbies are important for a person.B. Playing musical instruments is a Kind of hobby.C. If we often do something and don’t enjoy doing it, it will be our hobbies someday.D. A hobby can be gold if we dig it.1-5 D C B C C【练习10】You may hear about earthquakes, but do you know, what to do before, during and after an earthquake? Here is some advice for you:Before an earthquake. It’s necessary to prepare yourself and your family. All family members should know how to turn off gas, water and electricity and Know useful telephone numbers (doctor, hospital, police ,119, etc.). Never put heavy things over beds.During an earthquake. It’s important for each of you to stay calm( 冷静) . If you are indoors, quickly move to a safe place in the room such as under a strong desk or a strong table, the purpose is to protect yourself from falling objects. Stay away from windows, large mirrors, heavy furniture and so on. If you are cooking, turn off the gas.If you are outdoors, move to an open area like a playground. Move away from buildings, bridges and trees. If you are driving, stop the car as soon as possible, staying away from bridges and tall buildings Stay in your car.After an earthquake once the shaking has stopped, do not run out of the building at once. It’s better to wait and leave when it is safe.Check around you and help the people who are in trouble. If your building is badly broken you should leave it. If you smell or hear a gas, get everyone outside and open windows and doors. If you can do it safely, turn off the gas. Report it to the gas company.1. Which of the following is mentioned in the second paragraph？A. People should know how to turn on gas.B. People should know how to save water.C. People shouldn’t put heavy boxes over beds.D. People shouldn’t forget the phone numbers of others.2. When an earthquake happens, can help you deal with it.A. standing stillB. staying calmC. looking outsideD. moving indoors3. During an earthquake, if you are driving in an open area, you should .A. speed up your car B stop your car and stay inC. slow down your carD. stop your car and run out4. When the earth stops shaking, you should .A. check around you firstB. run out of the building at onceC. break the windows and doorsD. write a report to your company5. You can learn after reading the passage.A. what an earthquake is likeB. what to do to avoid earthquakeC. how an earthquake happensD. how to protect yourself in an earthquake1-5 D B B A D【练习11】Do you know the story about Vince? It was a true story. Vince was an English boy and he was eight years old. He didn’t like soap or water. Three or four times a day his mother said to him, “Vince, your hands are very dirty again.” Go and wash them.” But Vince never washed them well. He only put his hands in the water for a few seconds and then took them out again.Vince’s uncle and aunt lived in another city. One day they came to stay with Vince’s parents, and they brought their small son, Toby, with them. Toby was seven years old and he didn’t like soap or water, either. The boys sat with their parents for a few minutes and then they went outside. When they were playing, Vince looked at Toby’s hands and then went back to Toby’s parents and said proudly (骄傲地), “Toby’s hands are dirtier than mine, ” “Of course they are,” Toby said angrily. “You are one year older than I am.”1. Vince’s mother asked him to______ three or four times a day.A. wash his handsB.do his homeworkC. clean his bedroomD. wash his teeth2. When Vince saw Toby’s hands, he felt ________.A. SorryB. proudC. sadD. terrible3. Vince’s hands were a little______ than Toby’s.A. DirtierB. cleanerC. biggerD. smaller4. From the story we know that_______ .A. Vince liked soap and water, but Toby didn’t.B. Toby liked soap and water, but Vince didn’t.C. Vince and Toby liked soap and water.D. Vince and Toby didn’t like soap or water.5. How many people are there in the story?A. Four.B. FiveC. Six.D. Seven.1-5 ABBD【练习12】One day, there was a blind man called John sitting on the bench with a hat by his feet and a sign that read, “I am blind. Please help me.”A creative publicist (广告员) named Tom was walking by the blind man and stopped to see that the man only had a few coins in his hat. He put a few of his own coins in the hat.Without asking for permission (允许), he took the sign, turned it around and wrote a new message. Then he put the sign by the feet of the blind man and left.Later that afternoon the publicist returned to the blind man and noticed that his hat was almost full of bills (钞票) and coins. The blind man recognized (识别) his footsteps and asked if it was he who had changed his sign. He also wanted to know what the man wrote on it.The publicist said, “I just wrote the message a little differently.” He smiled and went on his way.The new sign read, “Spring has come, but I can’t see anything.”1. What’s the blind man’s name?A. Tom.B. John.C. Tony.D. Sorry, I don’t know.2. Who wrote a new message?A. The blind man.B. The teacher.C. The publicist.D. The farmer.3. How did the blind man recognize the publicist?A. By his sign.B. By his footsteps.C. By his voice.D. By his coins.4. When did the story happen?A. In spring.B. In summer.C. In autumn.D. In winter.5. What can we learn from the passage?A. Publicists are always curious (好奇) about everything.B. We can get more money by changing a sign.C. The blind man is not clever, so he has little money.D. The power of language is great.1-5CBCBA。
2023新教材高考数学二轮专题复习强化训练3排列组合二项式定理
强化训练3 排列、组合、二项式定理一、单项选择题(本大题共8小题，每小题5分，共40分，在每小题给出的四个选项中，只有一个是符合题目要求的)1．[2022·山东泰安模拟](x －1x)22展开式中的常数项为( )A ．C 1122 B ．－C 1122 C ．C 1222D ．－C 12222．3名男生2名女生站成一排照相，则2名女生相邻且都不站在最左端的不同的站法共有( )A ．72种B ．64种C ．48种D ．36种3．六名志愿者到北京、延庆、张家口三个赛区参加活动，若每个赛区两名志愿者，则安排方式共有( )A ．15种B ．90种C ．540种D ．720种4．[2022·湖南益阳一模]为迎接新年到来，某中学2022年“唱响时代强音，放飞青春梦想”元旦文艺晚会如期举行．校文娱组委员会要在原定排好的8个学生节目中增加2个教师节目，若保持原来的8个节目的出场顺序不变，则不同排法的种数为( )A ．36B ．45C ．72D ．905．[2022·山东德州二模]已知a >0，二项式(x ＋ax2)6的展开式中所有项的系数和为64，则展开式中的常数项为( )A ．36B ．30C ．15D ．106．[2022·山东淄博一模]若(1－x )8＝a 0＋a 1(1＋x )＋a 2(1＋x )2＋…＋a 8(1＋x )8，则a 6＝( )A ．－448B ．－112C ．112D ．4487．[2022·河北沧州二模](x －2x－1)5的展开式中的常数项为( )A ．－81B ．－80C ．80D ．1618．[2022·湖北十堰三模]甲、乙、丙、丁共4名学生报名参加夏季运动会，每人报名1个项目，目前有100米短跑、3 000米长跑、跳高、跳远、铅球这5个项目可供选择，其中100米短跑只剩下一个参赛名额，若最后这4人共选择了3个项目，则不同的报名情况共有( )A．224种B．288种C．314种D．248种二、多项选择题(本大题共4小题，每小题5分，共20分，在每小题给出的四个选项中，有多个符合题目要求，全部选对得5分，部分选对得2分，选错或多选得0分)9．[2022·河北唐山二模]已知(x－2x2)n的展开式中第3项与第8项的二项式系数相等，则( )A．n＝9B．n＝11C．常数项是672D．展开式中所有项的系数和是－110．在新高考方案中，选择性考试科目有：物理、化学、生物、政治、历史、地理6门．学生根据高校的要求，结合自身特长兴趣，首先在物理、历史2门科目中选择1门，再从政治、地理、化学、生物4门科目中选择2门，考试成绩计入考生总分，作为统一高考招生录取的依据．某学生想在物理、化学、生物、政治、历史、地理这6门课程中选三门作为选考科目，下列说法正确的是( )A．若任意选科，选法总数为C24B．若化学必选，选法总数为C12 C13C．若政治和地理至少选一门，选法总数为C12 C12C13D．若物理必选，化学、生物至少选一门，选法总数为C12 C12＋111．[2022·广东·华南师大附中三模]已知(a＋2b)n的展开式中第5项的二项式系数最大，则n的值可以为( )A．7 B．8C．9 D．1012．[2022·湖北荆州三模]已知二项式(2x－1x)n的展开式中共有8项，则下列说法正确的有( )A．所有项的二项式系数和为128B．所有项的系数和为1C．第4项和第5项的二项式系数最大D ．有理项共3项三、填空题(本题共4小题，每小题5分，共20分)13．[2022·山东烟台三模]若(1－ax )8展开式中第6项的系数为1792，则实数a 的值为________．14．[2022·辽宁辽阳二模]某话剧社计划在今年7月1日演出一部红色话剧，导演已经选好了该话剧的9个角色的演员，还有4个角色的演员待定，导演要从8名男话剧演员中选3名，从5名女话剧演员中选1名，则导演的不同选择共有________种．15．[2022·浙江卷]已知多项式(x ＋2)(x －1)4＝a 0＋a 1x ＋a 2x 2＋a 3x 3＋a 4x 4＋a 5x 5，则a 2＝______，a 1＋a 2＋a 3＋a 4＋a 5＝______．16．[2022·河北保定一模]2022年北京冬奥会的某滑雪项目中有三个不同的运动员服务点，现需将10名志愿者分配到这三个运动员服务点处，每处需要至少2名至多4名志愿者，则不同的安排方法一共有________种．强化训练3 排列、组合、二项式定理1．解析：（x －1x）22展开式中的常数项为C 1122 （－1）11＝－C 1122 .答案：B2．解析：将2名女生捆绑在一起，故2名女生相邻有A 22 种站法，又2名女生都不站在最左端，故有A 13 种站法，剩下3个位置，站3名男生有A 33 种站法，故不同的站法共有A 22 A 13 A 33 ＝36种． 答案：D3．解析：先从六名志愿者中选择两名志愿者到北京参加活动，有C 26 ＝15种方法，再从剩下的4名志愿者中选择2名志愿者到延庆参加活动，有C 24 ＝6种方法，最后从剩下的2名志愿者中选择2名志愿者到延庆参加活动，有C 22 ＝1种方法．由分步乘法原理得共有15×6×1＝90种方法．答案：B4．解析：采用插空法即可：第1步：原来排好的8个学生节目产生9个空隙，插入1个教师节目有9种排法； 第2步：排好的8个学生节目和1个教师节目产生10个空隙，插入1个教师节目共有10种排法，故共有9×10＝90种排法． 答案：D5．解析：令x ＝1，则可得所有项的系数和为（1＋a ）6＝64且a >0，解得a ＝1， ∵（x ＋1x 2）6的展开式中的通项T k ＋1＝C k 6 x 6－k（1x2）k ＝C k 6 x 6－3k ，k ＝0，1， (6)∴当k ＝2时，展开式中的常数项为C 26 ＝15. 答案：C6．解析：（1－x ）8＝（x －1）8＝[（1＋x ）－2]8＝a 0＋a 1（1＋x ）＋a 2（1＋x ）2＋…＋a 8（1＋x ）8，a 6＝C 28 ·（－2）2＝112.答案：C7．解析：（x －2x －1）5＝（x －2x －1）（x －2x －1）（x －2x －1）（x －2x －1）（x －2x－1），所以展开式中的常数项为（－1）5＋C 15 C 14 ×（－2）×（－1）3＋C 25 C 23 ×（－2）2×（－1）＝－81.答案：A8．解析：分两种情况讨论：①不选100米短跑，四名学生分成2名、1名、1名三组，参加除100米短跑的四个项目中的三个，有C 24 A 34 ＝144种；②1人选100米短跑，剩下三名学生分成2名、1名两组，参加剩下四个项目中的两个，有C 14 C 23 A 24 ＝144种．故他们报名的情况总共有144＋144＝288种． 答案：B9．解析：由C 2n ＝C 7n ，可得n ＝9，则选项A 判断正确；选项B 判断错误； （x －2x2）n 的展开式的通项公式为C k 9 x 9－k （－2）k x －2k ＝（－2）k C k 9 x 9－3k，令9－3k ＝0，则k ＝3，则展开式的常数项是（－2）3C 39 ＝－672.选项C 判断错误； 展开式中所有项的系数和是（1－212）9＝－1.判断正确．答案：AD10．解析：若任意选科，选法总数为C 12 C 24 ，A 错误； 若化学必选，选法总数为C 12 C 13 ，B 正确；若政治和地理至少选一门，选法总数为C 12 （C 12 C 12 ＋1），C 错误；若物理必选，化学、生物至少选一门，选法总数为C 12 C 12 ＋1，D 正确． 答案：BD11．解析：当（a ＋2b ）n的展开式中第4项和第5项的二项式系数相等且最大时，n ＝7； 当（a ＋2b ）n的展开式中第5项和第6项的二项式系数相等且最大时，n ＝9； 当（a ＋2b ）n的展开式中只有第5项的二项式系数最大时，n ＝8. 答案：ABC12．解析：由题设n ＝7，则T k ＋1＝C k 7 （2x ）7－k（－1x）k ＝（－1）k 27－k C k7 x7－3k2，A ．所有项的二项式系数和为27＝128，正确； B ．当x ＝1，所有项的系数和为（2－1）7＝1，正确；C ．对于二项式系数C k 7 ，显然第四、五项对应二项式系数C 37 ＝C 47 最大，正确； D ．有理项为7－3k2∈Z ，即k ＝0，2，4，6共四项，错误．答案：ABC13．解析：因为T 6＝T 5＋1＝C 58 （－ax ）5＝C 58 （－a ）5x 5＝C 38 （－a ）5x 5， 所以有：C 38 （－a ）5＝－56a 5＝1 792， 所以a 5＝－32, 解得a ＝－2. 答案：－214．解析：依题意，可得导演的不同选择的种数为C 38 ·C 15 ＝280. 答案：28015．解析：因为（x ＋2）（x －1）4展开式中x 2的系数为a 2，所以a 2＝C 34 （－1）3＋2C 24 （－1）2＝8.在多项式（x ＋2）（x －1）4＝a 0＋a 1x ＋a 2x 2＋a 3x 3＋a 4x 4＋a 5x 5中，令x ＝0，得a 0＝2；令x ＝1，得a 0＋a 1＋a 2＋a 3＋a 4＋a 5＝0.所以a 1＋a 2＋a 3＋a 4＋a 5＝－a 0＝－2.答案：8 －216．解析：根据题意得，这10名志愿者分配到三个运动员服务点处的志愿者数目为2，4，4或3，3，4，所以不同的安排方法共有C 210 C 48 C 44 A 22 A 33 ＋C 410 C 36 C 33 A 22 A 33 ＝22 050. 答案：22 050。
2023高考数学专题强化训练(一)
专题强化训练(一)一、单项选择题1.(2022·山东济南二模)函数f(x)=√16-x 2x的定义域是( A )A.[-4,0)∪(0,4]B.[-4,4]C.(-∞,-4]∪[4,+∞)D.[-4,0)∪[4,+∞)解析:由{16-x 2≥0,x ≠0,得-4≤x ≤4,且x ≠0,所以函数y=√16-x 2x 的定义域是[-4,0)∪(0,4].故选A.2.(2022·四川绵阳三模)已知函数f(x)=x x -1,则( D )A.f(x)为奇函数B.f(f(2))=1C.f(x)在(1,+∞)上单调递增D.f(x)的图象关于点(1,1)对称解析:由解析式知函数f(x)的定义域为{x|x ≠1},显然不关于原点对称,所以f(x)不是奇函数,A 错误;f(2)=2,则f(f(2))=f(2)=2,B 错误; 由f(x)=1+1x -1,可知f(x)在(1,+∞)上单调递减且图象关于点(1,1)对称,故C 错误,D 正确.故选D.3.(2022·陕西西安二模)设f(x)={2x+1-1,x ≤3,log 2(x 2-1),x >3,若f(x)=3,则x的值为( B )A.3B.1C.-3D.1或3解析:当x ≤3时,令2x+1-1=3,解得x=1,当x>3时,令log 2(x 2-1)=3,解得x=±3,这与x>3矛盾,所以x=1.故选B. 4.(2022·河北石家庄一模)函数f(x)=x 32x +2-x的部分图象大致是( A )解析:函数f(x)=x 32x +2-x的定义域为R,f(-x)=-f(x),故为奇函数,图象关于原点对称,据此排除B,D 选项;易知当x →+∞时,f(x)=x 32x +2-x>0,2x →+∞,2-x →0,x 3→+∞,因为指数函数y=2x 比幂函数y=x 3增长的速率要快,故f(x)→0,即f(x)在x →+∞时,图象往x 轴无限靠近且在x 轴上方,故A 选项符合.故选A.5.(2022·北京丰台区二模)已知偶函数f(x)在区间[0,+∞)上单调递减.若f(lg x)>f(1),则x 的取值范围是( C ) A.(110,1) B.(0,110)∪(1,+∞)C.(110,10) D.(0,110)∪(10,+∞)解析:因为偶函数f(x)在区间[0,+∞)上单调递减,所以f(x)在区间(-∞,0]上单调递增,则f(lg x)>f(1)等价于|lg x|<1,即-1<lg x<1,即lg 110<lg x<lg 10,解得110<x<10,即原不等式的解集为(110,10).故选C.6.(2022·天津河东区一模)设f(x)是定义域为R 的偶函数,且在(-∞,0)上单调递增,则( B ) A.f(log 314)>f(2-32)>f(2-23)B.f(2-32)>f(2-23)>f(log 314)C.f(log 314)>f(2-23)>f(2-32)D.f(2-23)>f(2-32)>f(log 314)解析:因为f(x)是定义域为R 的偶函数,且在(-∞,0)上单调递增,所以f(x)在(0,+∞)上单调递减,又log 34>1,0<2-32<2-23<1,所以f(2-32)>f(2-23)>f(log 34),即f(2-32)>f(2-23)>f(log 314).故选B.7.(2022·江苏苏州二模)已知f(x)是定义域为R 的偶函数, f(5.5)=2,g(x)=(x-1)f(x).若g(x+1)是偶函数,则g(-0.5)=( D ) A.-3 B.-2 C.2 D.3解析:g(x+1)为偶函数,则g(x)的图象关于直线x=1对称,即g(x)=g(2-x),即(x-1)f(x)=(1-x)f(2-x),即f(x)+f(2-x)=0,所以f(x)的图象关于点(1,0)中心对称,又f(x)是定义域为R 的偶函数,所以f(x)=-f(2-x)=-f(x-2),所以f(x-4)=f[(x-2)-2]=-f(x-2)=- [-f(x)]=f(x),即f(x-4)=f(x),所以f(x)的周期为4,所以f(5.5)=f(1.5)=f(-2.5)=f(2.5)=2,所以g(-0.5)=g(2.5)=1.5f(2.5)=3.故选D.8.(2022·天津市第四十七中学模拟预测)已知函数f (x )= {-12x ,x ≥0,2x -x 2,x <0,若f(2-a 2)>f(-|a|),则实数a 的取值范围是( A ) A.(-2,-√10-23)∪(√10-23,2) B.(-2,-1)∪(1,2)C.(-2,0)∪(0,2)D.(-1,0)∪(0,1)解析:作出函数f(x)={-12x ,x ≥0,2x -x 2,x <0的图象如图,因为-|a|≤0,若2-a 2<0,由f(x)在(-∞,0)上单调递增,且f(2-a 2)>f(-|a|),则2-a 2>-|a|,解得√2<|a|<2; 若2-a 2≥0,则-12(2-a 2)>-2|a|-a 2,解得√10-23<|a|≤√2. 综上,√10-23<|a|<2,解得-2<a<-√10-23或√10-23<a<2.所以实数a 的取值范围是(-2,-√10-23)∪(√10-23,2).故选A.二、多项选择题9.(2022·山东济南一中模拟预测)设函数f(x)={log 2(x -1),x >2,2x -3,x ≤2,则以下结论正确的为( BC ) A.f(x)为R 上的增函数B.f(x)有唯一的零点x 0,且1<x 0<2C.若f(m)=5,则m=33D.f(x)的值域为R解析:作出f(x)的图象如图所示.对于A,取特殊值:f(2)=1,f(3)=1,故A 错误;对于B,由图象可知,f(x)有唯一的零点x 0,f(x)在(-∞,2]上单调递增,且f(1)<0,f(2)>0,故B 正确;对于C,当x ≤2时,2x -3≤1,故log 2(m-1)=5,解得m=33,故C 正确; 对于D,f(x)的值域为(0,+∞)∪(-3,1]=(-3,+∞),故D 错误.故选BC. 10.(2022·重庆模拟预测)定义在(-1,1)上的函数f(x)满足f(x)-f(y)=f(x -y 1-xy),且当x ∈(-1,0)时,f(x)<0,则有( ABC )A.f(x)为奇函数B.存在非零实数a,b,使得f(a)+f(b)=f(12)C.f(x)为增函数D.f(12)+f(13)>f(56)解析:令x=0,y=0,得f(0)-f(0)=f(0),所以f(0)=0;令x=0,y=x,得f(0)-f(x)=f(-x),故-f(x)=f(-x),所以f(x)为奇函数,A 正确;任取-1<x 1<x 2<1,则f(x 1)-f(x 2)=f(x 1-x 21-x 1x 2),因为x 1-x 21-x 1x 2+1=x 1-x 2+1-x 1x 21-x 1x 2=(1+x 1)(1-x 2)1-x 1x 2>0,故-1<x 1-x 21-x 1x 2<0,f(x 1)-f(x 2)=f(x 1-x 21-x 1x 2)<0,f(x 1)<f(x 2),故f(x)为增函数,C 正确; f(12)+f(13)=f(12)-f(-13)=f(12+131+12×13)=f(57)<f(56),D 错误;若f(a)+f(b)=f(a)-f(-b)=f(a+b1+ab )=f(12),则a+b1+ab=12,则2a+2b=1+ab,a=1-2b2-b =2+3b-2,当b∈(-1,1)时,a∈(-1,1),所以存在非零实数a,b,使得f(a)+f(b)=f(12),B正确.故选ABC.11.若函数f(x)满足:对定义域内任意的x1,x2(x1≠x2),有f(x1)+f(x2)>2f(x1+x22),则称函数f(x)具有H性质.则下列函数中具有H性质的是( ACD )A.f(x)=(12)xB.f(x)=ln xC.f(x)=x2(x≥0)D.f(x)=tan x(0≤x<π2)解析:若对定义域内任意的x1,x2(x1≠x2),有f(x1)+f(x2)>2f (x1+x22),则点(x1,f(x1)),(x2,f(x2))连线的中点在点(x1+x22,f(x1+x22))的上方,如图(其中a=f(x1+x22),b=f(x1)+f(x2)2).根据函数f(x)=(12)x,f(x)=ln x,f(x)=x2(x≥0),f(x)=tan x(0≤x<π2)的图象可知,函数f(x)=(12)x,f(x)=x2(x≥0),f(x)=tan x(0≤x<π2)具有H性质,函数f(x)=ln x不具有H性质.故选ACD.12.(2022·福建福州模拟预测)设函数f(x)的定义域为R,f(x-1)为奇函数,f(x+1)为偶函数,当x ∈(-1,1)时,f(x)=-x 2+1,则下列结论正确的是( ABD ) A.f(72)=-34B.f(x+7)为奇函数C.f(x)在(6,8)上单调递减D.方程f(x)+lg x=0仅有6个实数解解析:因为f(x+1)为偶函数,故f(x+1)=f(-x+1),令x=52得f(72)=f(-52+1)=f(-32),因为f(x-1)为奇函数,故f(x-1)=-f(-x-1),令x=-12得f(-32)=-f(12-1)=-f(-12),其中f(-12)=-14+1=34,所以f(72)=f(-32)=-f(-12)=-34,A 正确;因为f(x-1)为奇函数,所以f(x)的图象关于点(-1,0)中心对称,又f(x+1)为偶函数,则f(x)的图象关于直线x=1对称,所以f(x)的周期为4×2=8,故f(x+7)=f(x-1),所以f(-x+7)=f(-x-1)=-f(x-1)= -f(x-1+8)=-f(x+7),从而f(x+7)为奇函数,B 正确;f(x)=-x 2+1在x ∈(-1,0)上单调递增,又f(x)的图象关于点(-1,0)中心对称,所以f(x)在(-2,0)上单调递增,且f(x)的周期为8,故f(x)在(6,8)上单调递增,C 错误;根据题目条件画出函数f(x)与y=-lg x 的图象,如图所示,其中y=-lg x 单调递减且-lg 12<-1,所以两函数图象有6个交点,故方程f(x)+lg x=0仅有6个实数解,D 正确.故选ABD.三、填空题13.(2022·广东深圳二模)已知函数f(x)=ln(e x +1)-kx 是偶函数,则k= .解析:由题意知f(x)=ln(e x +1)-kx 是偶函数,则x ∈R,f(-x)=f(x), 即ln(e -x +1)-k(-x)=ln(e x +1)-kx, 即ln(e x +1)-x+kx=ln(e x +1)-kx, 即(k-1)x=-kx,解得k=12.答案:1214.(2022·山东烟台一模)已知f(x)为R 上的奇函数,且f(x)+ f(2-x)=0,当-1<x<0时,f(x)=2x ,则f(2+log 25)的值为 . 解析:由题设,f(2-x)=-f(x)=f(-x),故f(2+x)=f(x),即f(x)的周期为2,所以f(2+log 25)=f(2×2+log 254)=f(log 254)=-f(log 245),且-1<log 245<0,所以f(2+log 25)=-2log 245=-45.答案:-4515.(2022·湖南湘潭三模)已知a >0,且a ≠1,函数f (x )= {log a (2x 2+1),x ≥0,a x,x <0,若f(f(-1))=2,则a= ,f(x)≤4的解集为 .解析:①由题可知,f(f(-1))=f(a -1)=log a (2a -2+1)=2,则a 2=2a -2+1,即a 4-a 2-2=0,解得a 2=2,故a=√2.②当x ≥0时,f(x)=log √2(2x 2+1)≤4,解得0≤x ≤√62;当x<0时, f(x)=(√2)x≤4恒成立,故不等式的解集为(-∞,√62]. 答案:√2 (-∞,√62]16.(2022·山东菏泽一模)已知奇函数f(x)在区间(-∞,0)上是增函数,且f(-2)=-1,f(1)=0,当x>0,y>0时,都有f(xy)=f(x)+f(y),则不等式log 3|f(x)+1|<0的解集为 .解析:法一 不等式log 3|f(x)+1|<0等价于0<|f(x)+1|<1,即0<f(x)+1<1或-1<f(x)+1<0,即-1<f(x)<0或-2<f(x)<-1,因为f(x)是奇函数,且f(-2)=-1,f(1)=0,所以f(2)=1,f(-1)=0,故f(1)= f(2×12)=f(2)+f(12)=0 ,则f(12)=-1 ,f(14)=f(12×12)=f(12)+f(12)=-2,f(-4)=-f(4)=-f(2)-f(2)=-2.又奇函数f(x)在区间(-∞,0)上是增函数,故f(x)在区间(0,+∞)上也是增函数,故-1<f(x)<0,即f(-2)<f(x)<f(-1)或f(12)<f(x)<f(1),此时x ∈(-2,-1)∪(12,1) ;而-2<f(x)<-1,即f(-4)<f(x)<f(-2) 或f(14)<f(x)<f(12),此时x ∈(-4,-2)∪(14,12),故不等式l o g 3|f (x )+1|<0的解集为(-4,-2)∪(-2,-1)∪(14,12)∪(12,1).法二 因为f(x)为奇函数,且f(-2)=-1,所以f(2)=1,又当x>0,y>0时,都有f(xy)=f(x)+f(y),所以当x>0时,可设f(x)=log a x(a>0,且 a ≠1),由f(2)=1可得a=2,所以f(x)={log 2x (x >0),-log 2(-x )(x <0),由log 3|f(x)+1|<0可得-2<f(x)<0且f(x)≠-1. 作出函数f(x)的图象如图,由图象可知,不等式的解集为(-4,-2)∪(-2,-1)∪(14,12)∪(12,1).答案:(-4,-2)∪(-2,-1)∪(14,12)∪(12,1)。
2024年高考语文第二轮专题复习强化训练：语言文字运用(附答案) (1)
2024年高考语文第二轮专题复习强化训练：语言文字运用阅读下面的文字，完成下题。
事有凑巧，在不同的时间和不同的地方，我听见过三位老师讲“破釜沉舟”这个成语。
第一位教师是这样讲的：“‘破釜沉舟’表示坚决的意思。
做事一定要坚决。
无论做什么，只要是正当的、应该做的事，就必须抱定只许前进而不许后退、只许胜利而不许失败的决心，只有这样才能得到成功。
如果(______________)，工作还没开始就准备下失败的退路，那样一定不会成功。
①当然，②前进的目的必须正确。
③在这一点上，④我们不能跟古人相提并论。
由于时代的局限，古人，尤其是封建统治阶级的人，做事的目的在今天看来很多是成问题的，下定决心做好事是应当的，如果坚决做坏事，那就不应当了。
”第二位教师是另一种讲法，他说：“‘釜’就是锅，‘舟’就是船。
‘破’和‘沉’都是动词。
‘破釜’是‘使釜破’的意思，也就是把锅砸碎；‘沉舟’是‘使舟沉’的意思，也就是把船凿沉。
这样用法的动词叫作‘使动词’。
同是做饭的工具，古代叫‘釜’，现代叫‘锅’；同是水上运输工具，古代叫‘舟’，现代叫‘船’；这是古今词汇的演变。
像古代叫‘冠’，现代叫‘帽子’，古代叫‘履’，现代叫‘鞋’，都是这种情形。
曹植《七步诗》里有‘豆在釜中泣’的句子，______________，这里的‘釜’和‘舟’跟‘破釜沉舟’里的‘釜’和‘舟’意思相同。
”第三位教师讲得比较简单，话说得比较少。
他这样讲：“项羽渡河进攻秦朝的军队，渡河之后，把造饭的锅砸碎，把船凿沉，断了自己的退路，以示有进无退的决心，终于把秦军打败了。
后来大家就用‘破釜沉舟’这个成语表示下定最大的决心，不顾任何牺牲的意思。
”1．将下列俗语填入文中括号内，恰当的一项是（）A．干打雷不下雨 B．又吃鱼又嫌腥C．前怕狼后怕虎 D．首尾不能兼顾2．文中画线的语句中有一处表述不当，请标出原句序号后再做修改，并使修改后的语句与上下文的衔接流畅自然。
3．请在横线处仿照上句补写恰当的句子，要求内容正确贴切，语意完整连贯。
专题三 标点与病句辨析-2022-2023学年中考语文一轮复习强化训练(全国版)(解析版)
2022～2023学年语文中考一轮复习强化训练专题三标点与病句辨析一、选择题。
1.（2022·广西梧州·九年级期末）下列句子中标点符号使用有误的一项是（）。
A.熟悉的树木、村庄、桥梁……等都在不停地后退，成为杜小康眼中的遥远之物。
B.现在，占据他心灵的全部是前方：还要走多远？前方是什么样子？C.杜雍和大叫了一声“我的鸭子”，几乎晕倒在地上。
D.后来，父子俩都在心里清楚了这一点：他们已根本不可能回避孤独了。
【答案】A【解析】本题考查标点符号。
A.“等”和省略号不能同时使用；删去“等”或省略号；故选A。
2.（2022·山东·九年级专题练习）文中四处标点符号使用错误的一项（）。
一次次在梦中回到那个老屋里，①鸡鸣犬吠，蛙声蝉音，青灯黄卷，飘雪夜读，②一次次在梦中看见了那浩渺的水荡，水天一色，白帆点点，孤鹜落霞，连荷碧天，③麦浪滚滚，稻花飘．香。
④还是那个老屋里，凄风苦雨，雪窖冰天，清水冷灶，饥不择食；还是那个浩渺的水荡，_____，寒耕热耘，披星戴月，风cān露宿。
A.①B.②C.③D.④【答案】B【解析】本题考查标点符号。
第②句“一次次在梦中看见了那浩渺的水荡，水天一色，白帆点点，孤鹜落霞，连荷碧天”与“一次次在梦中回到那个老屋里，鸡鸣犬吠，蛙声蝉音，青灯黄卷，飘雪夜读”为并列关系，中间应使用分号；即：②前的逗号改为分号。
故选B。
3.（2022·广西河池·九年级期末）下列各句中，标点符号使用正确的一项是（）。
A.这所美丽的乡村小学规模不大，全校只有四、五百学生。
B.原西南师范大学校长邱玉辉、高级工程师彭燕华、重庆大学教授尹超……等多位国内人工智能专家出席了大会。
C.医学专家指出，大量快速地进食冷饮，会损伤孩子稚嫩的胃黏膜，引起急性胃痉挛，导致腹痛，腹泻，食欲不振。
D.年少时，眼神澄澈，心地纯良：长大后，受到名利、欲望、贪婪等熏染，变了质，走了味，失了魂。
高中物理必修三专题强化训练—闭合电路的功率、故障分析
高中物理必修三专题强化训练—闭合电路的功率、故障分析[学习目标] 1.会计算闭合电路的功率和效率，掌握电源的输出功率随外电阻变化的图像.2.会结合闭合电路欧姆定律和部分电路欧姆定律分析电路故障．一、闭合电路的功率问题1.电源的输出功率对于纯电阻电路，P出＝I2R ＝⎝⎛⎭⎪⎫ER＋r2R＝E2R－r2R＋4r，当R＝r时，电源的输出功率最大，其最大输出功率为P m＝E24r.电源输出功率随外电阻变化曲线如图1所示．图1 2．电源的效率指电源的输出功率与电源的总功率之比，即η＝P出P总×100%＝IUIE×100%＝UE×100%.对于纯电阻电路，电源的效率η＝I2RI2R＋r×100%＝RR＋r×100%＝11＋rR×100%，所以当R增大时，效率η提高．当R＝r(电源有最大输出功率)时，效率仅为50%，效率并不高．如图2所示，电路中E＝3 V，r＝0.5 Ω，R0＝1.5 Ω，滑动变阻器的最大阻值为10 Ω.图2(1)滑动变阻器接入电路的阻值R为多大时，定值电阻R0上消耗的功率最大？最大为多大？(2)滑动变阻器接入电路的阻值R为多大时，滑动变阻器上消耗的功率最大？最大为多大？答案(1)0278W(2)2 Ω98W解析(1)定值电阻R0上消耗的功率：P＝I2R0，R0不变，当电流最大时功率最大，此时应有电路中电阻最小，即当R＝0时，R0上消耗的功率最大：P0m＝E2R0＋r2R0＝321.5＋0.52×1.5 W＝278W.(2)将电阻R0和电源等效成新的电源，滑动变阻器上消耗的功率就是等效电源的输出功率．当R＝r＋R0＝2 Ω时，滑动变阻器上消耗的功率最大，为：P m＝E24R＝324×2W＝98W.功率最大值的求解方法1．对定值电阻来说，其电流最大时功率也最大．2．电源的输出功率在外电阻等于内阻时最大，若不能相等，外电阻越接近内阻时，电源的输出功率越大．3.如图3，求解滑动变阻器R2消耗的最大功率时，可把定值电阻R1等效为电源内阻的一部分，则R2＝R1＋r时，R2上消耗的功率最大．图3针对训练1如图4所示，电源的内阻不可忽略，在滑片从最右端向最左端滑动的过程中，下列说法正确的是()图4A．电源的内耗功率减小B．电源消耗的总功率增大C．电阻R1的功率增大D．电源的输出功率减小答案 B解析滑片向左移动，R3减小，电路总电阻减小，总电流I增大，由P r＝I2r，P ＝IE，可知电源的内耗功率和电源消耗的总功率均增大，故A错误，B正确；由于总电流增大，因此内电压变大，路端电压减小，则电阻R1的功率将减小，故C 错误；当外电路的电阻与电源的内阻相等时，电源的输出功率最大，由于电阻的阻值情况未知，因此输出功率的变化无法确定，故D错误．(2020·河北鸡泽县期末)如图5所示，线段A为某电源的U－I图线，线段B 为某电阻R的U－I图线，由上述电源和电阻组成闭合电路时，求：图5(1)电源的输出功率P出是多大？(2)电源内部损耗的电功率P内是多少？(3)电源的效率η是多大？答案(1)4 W(2)2 W(3)66.7%解析(1)从图线A可读出，电源的电动势E＝3 V，内阻r＝EI短＝36Ω＝0.5 Ω从图像的交点可读出：路端电压U＝2 V，电路电流I＝2 A，则电源的输出功率为P出＝UI＝2×2 W＝4 W.(2)电源内部损耗的电功率P内＝I2r＝22×0.5 W＝2 W(3)电源的总功率为P总＝IE＝2×3 W＝6 W故电源的效率为η＝P出P总×100%＝46×100%≈66.7%.1.稳定电路的U－I图像有两种：一是电源的U－I图像(如图6中a)；二是用电器的U－I图像，而用电器的U－I图像又分两类：线性(图中b)和非线性(图中c)．图62．两种图像的交点坐标表示该用电器单独与电源串联的工作电流和路端电压(也是用电器两端的电压)．如图，电源的输出功率分别为P b＝U1I1，P c＝U2I2.二、电路故障分析1．常见故障：断路、短路．2．常用方法：假设法假设某电阻发生断路(或短路)，根据闭合电路动态分析方法判断实际现象与题中情景是否相符，进而找出电路故障．如图7所示的电路中，闭合开关S后，灯L1、L2都正常发光，后来由于某种故障，灯L2突然变亮(未烧坏)，电压表的读数增大，由此可推断，该故障可能是()图7A．电阻R1断路B．电阻R2短路C．灯L1两接线柱间短路D．电阻R2断路答案 D解析因为电压表的读数增大，所以路端电压增大，电源的内电压减小，说明总电流减小，则电路的总电阻增大，若电阻R1断路，会导致总电阻增大，总电流减小，灯L2变暗，选项A错误．若电阻R2短路，灯L2将不亮，选项B错误．若灯L1两接线柱间短路，电路的总电阻减小，总电流增大，路端电压减小，电压表的读数减小，不符合题意，选项C错误．若电阻R2断路，电路的总电阻增大，总电流减小，电压表的读数增大，因为总电流减小，所以内电压和灯L1、R1并联部分电压减小，灯L2两端电压增大，灯L2变亮，选项D正确．针对训练2如图8所示，灯泡L1、L2原来都正常发光，在两灯突然熄灭后，用电压表测得c、d间电压比灯泡正常发光时的电压高，故障可能是(假设电路中仅有一处故障)()图8A．a、c间断路B．c、d间断路C．b、d间断路D．b、d间短路答案 B解析因电路中L1、L2、R及电源串联，电路中只有一处故障且两灯不亮，故电路中必是断路，D错误．电路中无电流，但c、d间电压升高，是因为c、d间断路，c、d两点分别与电源正、负极等电势，故B正确．1.(多选)(2020·湖北十堰市期末)在如图1所示的电路中，P为滑动变阻器的滑片，电表均为理想电表，下列说法正确的是()图1A．在P向右移动的过程中，电流表的示数变大B．在P向右移动的过程中，电压表的示数变大C．当P移到滑动变阻器的右端时，电源内部消耗的电功率最大D．当P移到滑动变阻器的右端时，电源的效率最高答案AC解析滑动变阻器的滑片P向右移动，电路总电阻减小，根据I＝ER总可知，电流表的示数变大，根据E＝U＋Ir可知电压表的示数减小，故A正确，B错误；当P移到滑动变阻器的右端时，外电阻R最小，根据I＝ER总可知，电路中的电流最大，根据P内＝I2r可知此时电源内部消耗的电功率最大，故C正确；根据效率η＝RR＋r×100%可知，此时电源的效率最低，故D错误．2.(多选)(2020·江苏卷)某汽车的电源与启动电机、车灯连接的简化电路如图2所示．当汽车启动时，开关S闭合，电机工作，车灯突然变暗，此时()图2A．车灯的电流变小B．路端电压变小C．电路的总电流变小D．电源的总功率变大答案ABD解析汽车启动时，车灯变暗，I灯减小，U灯减小，路端电压变小，则电路的总电流变大，故A、B正确，C错误；由P＝IE知电源的总功率变大，故D正确．3.(2020·长沙一中期中)如图3所示，直线OAC为某一直流电源的总功率随电流I 变化的图线，曲线OBC表示同一直流电源内部的热功率随电流I变化的图线．若A、B点的横坐标均为1 A，那么AB线段表示的功率为()图3A．1 W B．6 WC．2 W D．2.5 W答案 C解析电源的总功率P＝EI，C点表示I＝3 A，P＝9 W，则电源的电动势E＝3 V，由题图知，C点表示外电路短路，电源内部热功率等于电源的总功率，则有P＝I2r，代入解得，r＝1 Ω，所以AB段表示的功率为P AB＝EI′－I′2r＝3×1 W－12×1 W ＝2 W，故C正确，A、B、D错误．4.(多选)(2021·泉州泉港区一中高二期末)如图4所示，直线A为电源a的路端电压与电流的关系图像，直线B为电源b的路端电压与电流的关系图像，直线C为一个电阻R两端的电压与电流的关系图像．将这个电阻R分别接到a、b两电源上，那么()图4A．R接到b电源上，电源的输出功率较大B．R接到b电源上，电源的效率较高C．R接到a电源上，电源的输出功率较大，但电源效率较低D．R接到b电源上，电阻的发热功率和电源的效率都较高答案BC解析电源的效率η＝P出P总×100%＝I2RI2R＋r×100%＝RR＋r×100%，由电源U－I图像斜率的绝对值表示内阻可知，b电源的内阻r较小，R接到b电源上，电源的效率较高，故B正确；当电阻R与电源组成闭合电路时，电阻R的U－I图线与电源的U－I图线的交点表示电阻R的工作状态，交点的纵坐标表示路端电压，横坐标表示电流，两者乘积表示电源的输出功率，由题图知，R接到a电源上，电源的输出功率较大，故C正确，A、D错误．5.将一电源与一电阻箱连接成闭合回路，测得电阻箱所消耗的功率P随电阻箱读数R变化的曲线如图5所示，由此可知()图5A．电源最大输出功率可能大于45 WB．电源内阻一定等于5 ΩC．电源电动势为45 VD．电阻箱所消耗的功率P最大时，电源效率大于50%答案 B解析由题图可知，电阻箱所消耗的功率P的最大值为45 W，所以电源最大输出功率为45 W，选项A错误；由电源输出功率最大的条件可知，电源输出功率最大时，外电路电阻的阻值等于电源内阻，所以电源内阻一定等于5 Ω，选项B 正确；由题图可知，电阻箱所消耗的功率P为最大值45 W时，电阻箱读数为R＝5 Ω，电流I＝PR＝3 A，电源电动势E＝I(R＋r)＝30 V，选项C错误；电阻箱所消耗的功率P最大时，电源效率为50%，选项D错误．6.(多选)如图6所示的电路中，由于某一电阻发生短路或断路，使A灯变暗，B 灯变亮，则故障可能是()图6A．R2短路B．R2断路C．R3断路D．R4断路答案BC解析由于A灯串联于干路中，且故障发生后A灯变暗，可知电路中总电流变小，即电路总电阻变大，由此推知，故障应为某一电阻断路且电路仍然接通，故选项A、D错误；若R2断路，R1和B灯所在支路的电压增大，而R2的断路又使B灯分得的电压增大，故B灯变亮，推理结果与现象相符，故选项B正确；若R3断路，引起与之并联的支路(即R1所在支路)中的电流增大，B灯中分得的电流变大，B灯变亮，故选项C正确．7．(多选)如图7所示，图中直线①表示某电源的路端电压与电流的关系图线，图中曲线②表示该电源的输出功率与电流的关系图线，则下列说法正确的是()图7A．电源的电动势为50 VB．电源的内阻为253ΩC．电流为2.5 A时，外电路的电阻为15 ΩD．输出功率为120 W时，输出电压是30 V答案ACD解析电源的路端电压和电流的关系为：U＝E－Ir，显然直线①的斜率的绝对值等于r，纵轴的截距为电源的电动势，从题图中看出E＝50 V，r＝50－206－0Ω＝5 Ω，A正确，B错误；当电流为I1＝2.5 A时，由回路中电流I1＝Er＋R外，解得外电路的电阻R外＝15 Ω，C正确；当输出功率为120 W时，由题图中P－I关系图线看出对应干路电流为4 A，再从U－I图线读取对应的输出电压为30 V，D正确．。
整章强化训练专题练习(四)含答案高中物理选修3-1磁场
高中物理专题复习选修3-1磁场单元过关检测考试范围：单元测试；满分：100分注意事项：1．答题前填写好自己的姓名、班级、考号等信息2．请将答案正确填写在答题卡上第I卷（选择题）请点击修改第I卷的文字说明评卷人得分一、单选题1．如图所示，在xOy平面的第一、四象限内存在着方向垂直纸面向外，磁感应强度为B的匀强磁场，在第四象限内还存在方向沿-y方向、电场强度为E的匀强电场.从y轴上坐标为（0，a）的P点向第一象限的磁场区发射速度大小不等的带︒-︒角，且在xOy平面内.结正电的同种粒子，速度方向范围是与+y方向成30150果所有粒子经过磁场偏转后都垂直打到x轴上，然后进入第四象限内的正交电磁场区.已知带电粒子电量为+q，质量为m，粒子重力不计.（1）所有通过第一象限磁场区的粒子中，求粒子经历的最短时间与最长时间的比值；（2）求粒子打到x轴上的范围；（3）从x轴上x=a点射入第四象限的粒子穿过正交电磁场后，从y轴上坐标为（0，-b）的Q点射出电磁场，求该粒子射出电磁场时的速度大小.2．如图所示，在平面直角坐标系xO y内，第Ⅰ象限的等腰直角三角形MNP区域内存在垂直于坐标平面向外的匀强磁场，y＜0的区域内存在着沿y轴正方向的匀强电场．一质量为m、电荷量为q的带电粒子从电场中的Q（-2h，-h）点以速度v0水平向右射出，经坐标原点O处射入第I象限，最后以垂直于PN的方向射出磁场．已知MN平行于x轴，N点的坐标为（2h，2h），不计粒子的重力．求：（1）电场强度的大小E；（2）磁感应强度的大小B；（3）粒子在磁场中运动的时间t．3．如图甲所示的控制电子运动装置由偏转电场、偏转磁场组成。
偏转电场处在加有电压U、相距为d的两块水平平行放置的导体板之间，匀强磁场水平宽度一定，竖直长度足够大，其紧靠偏转电场的右边。
大量电子以相同初速度连续不断地沿两板正中间虚线的方向向右射入导体板之间。
当两板间没有加电压时，这些电子通过两板之间的时间为2t0；当两板间加上图乙所示的电压U时，所有电子均能通过电场、穿过磁场，最后打在竖直放置的荧光屏上。
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专题强化训练(三)中国特色社会主义经济制度
与经济体制
1．解析：从注中信息可知，国有经济在国民经济中的控制力有所增强而不是削弱，①错误。
民营经济是社会主义市场经济的重要组成部分，在我国所有制结构中的地位不变，②错误。
国有企业数量不断下降，很可能是因为国有企业不断并购重组，③正确。
从图中可以看出，2010—2018年，500强入围民营企业数量不断增加，这表明大量优秀民营企业在改革开放中快速崛起，不断做强做大，④正确。
答案：B
2．解析：本题考查我国的基本经济制度。
“三个没有变”表明公有制经济与非公有制经济都是我国经济社会发展的重要基础，民营经济是我国社会主义市场经济的重要组成部分，①②符合题意；生产资料公有制是社会主义经济制度的基础，③错误；国有经济在我国国民经济中发挥主导作用，公有制经济在我国国民经济中居于主体地位，④错误。
答案：A
3．解析：本题考查所有制、企业的相关知识。
②错误，国企应实行股份制改革；④错误，国有企业经营的主要目的是增加经营性收入；深化国有企业改革，推动国有资本做强做优做大，需要健全市场化经营机制，让国有企业直面市场竞争同时要选拔培养造就一支懂市场、善经营的高素质企业家队伍，从而提升国有企业管理水平，故①③符合题意。
答案：B
4．解析：本题考查我国的基本经济制度。
①符合题意，非公有制经济是社会主义基本经济制度的重要组成部分，不能离场；②表述错误，不能说非公有制经济比公有制经济更能适应生产力发展的要求，它们都与社会主义初级阶段的生产力发展水平相适应；③表述错误，公有制经济与非公有制经济在国民经济中地位不同，在社会主义市场经济中地位平等；④符合题意，非公有制经济和公有制经济平等竞争有利于激发我国经济活力和创造力。
答案：B
5．解析：本题考查集体经济。
材料中的合作共享模式发挥了市场作用，盘活了村集体资源，巩固和完善了农村基本经营制度，提升了村级集体的扶贫带贫能力，①②符合题意；这些发展模式是为了扶贫带贫，③与题意不符；这些模式并没有改变农村集体经济的所有制性质，④说法错误。
答案：A
6．解析：本题考查按要素分配。
该家庭承包的2公顷土地以每年每公顷15 000元转包给一私营农业公司经营，这属于按土地要素分配，共1 5 000×2＝30 000(元)；甲在该公司打工，月工资1 500元，这属于按劳动要素分配，共1 500×12＝18 000(元)；乙在一家中型国有企业工作，工资、薪金年收入40 000元，这属于按劳分配；当年乙通过转让专利技术获得收入3 500元，这属于按技术要素分配。
因此该家庭当年按要素分配所得收入为30 000＋18 000＋3 500＝51 500(元)，故B、C、D错误，选A。
答案：A
7．解析：本题考查效率与公平的关系。
广东省政府依据国家法律法规，结合当地经济社会发展水平，决定提高全省企业职工最低工资标准，说明政府坚持在经济增长的同时实现居民收入同步增长，经济社会发展的同时更应注重实现社会公平，③④符合题意；最低工资标准的提高属于初次分配，不属于再分配，①说法错误；材料中的做法是发挥宏观调控的作用，不是市场对资源配置的决定性作用，②说法错误。
答案：D
8．解析：本题考查社会公平的知识。
允许部分人先富起来，会拉大人们的收入差距，不利于促进社会公平，①错误；我国实行按劳分配为主体，多种分配方式并存的分配制度，②中“并重”说法错误；提高个税起征点，调节过高收入，提高低收入者收入，缩小居民收入差距，有利于促进社会公平，③④符合题意。
答案：C
9．解析：本题考查市场调节的局限性、宏观调控等知识。
依法严厉打击虚假宣传、虚假广告、制售假冒伪劣产品等扰乱市场秩序、欺诈消费者等各类违法行为，体现了市场调节的自发性，扰乱了公平、公正的市场秩序，政府应发挥“有形的手”的作用，加大对保健品市场的事中事后监督和管理，②③正确；保健行业的乱象，源于市场调节的自发性，故①错误；我国要形成以道德为支撑，法律为保障的社会信用制度，维护消费者合法权益，④错误。
答案：B
10．解析：本题考查宏观调控及供给侧改革的知识。
推进房地产
去库存，可通过降低银行信贷利率，以降低购房成本，增加商品房购买数量，达到房地产去库存的目标，D项传导路径正确；征收房地产税，会减少购房需求，达不到房地产去库存的目标，A项传导错误；严格土地审核，减少土地供应量，会减少新增商品房数量，但商品房数量仍会增加，B项传导错误；推进户籍制度改革，鼓励农民工进城落户，有利于推进房地产去库存而不是增加住房供给，C项传导错误。
答案：D
11．解析：本题考查财政政策、宏观调控。
国家增发国债，有助于筹集资金，在重点领域扩大支出规模，持续增加对民生领域的投入，扩大社会总需求，从而刺激企业扩大生产，增加就业，进一步使居民收入增加，消费水平提升，促进经济社会发展。
故C符合题意，排除A、B、D。
答案：C
12．解析：本题考查社会主义市场经济的基本特征。
京张高铁项目由中国铁路总公司、北京市和河北省、张家口市政府联合投资，说明社会主义市场经济能够发挥国家集中力量办大事的优势，③正确；京张高铁将力促张家口借助2022年冬奥会摘掉贫困的帽子，表明最终实现共同富裕是发展社会主义市场经济的根本目标，④符合题意。
修建京张高铁体现了国家促进资源整合与优化，但材料不能体现推动工业化与信息化深度融合，排除①；材料没有体现增强发展的可持续性，②不选。
答案：D
13．结合材料，运用经济生活知识，分析说明推动民营经济做优
做强的重要性以及如何助推民营经济走出困境，健康成长。
解析：民营经济属于非公有制经济，是社会主义市场经济的重要组成部分，是经济社会发展的重要基础。
发展民营经济有利于大量吸纳劳动者就业，增加财政收入等，第一小问从以上几点进行表述即可。
根据材料，结合所学知识，第二小问从坚持和完善我国基本经济制度，加强宏观调控，支持企业自主创新能力的提升等角度进行分析即可。
答案：重要性：非公有制经济是社会主义市场经济的重要组成部分，是经济社会发展的重要基础。
发展民营经济有利于促进经济发展，促进创新，增加就业和财政收入。
措施：①坚持和完善公有制为主体、多种所有制经济共同发展的基本经济制度，毫不动摇地鼓励、支持、引导非公有制经济发展，国家保证各种所有制经济依法平等使用生产要素，公开、公平、公正地参与市场竞争。
②加强宏观调控，健全社会信用体系，综合运用经济、法律以及行政手段对民营经济进行调节，加大对民营企业的信贷、资金支持力度，要贯彻落实市场准入负面清单制度等，为民营经济发展营造良好环境。
③要支持和帮助民营企业不断提高自主创新能力，使民营企业依靠技术进步、科学管理等手段，诚信经营，提高市场竞争力。
14．结合材料，运用“走进社会主义市场经济”的知识分析说明我国价格改革是如何得到有序推进的。
解析：解答本题，首先要注意把握考查的知识范围是“走进社会主义市场经济”的知识，设问是“分析说明我国价格改革是如何得到有序推进的”。
然后分析材料和设问，根据材料和设问联系课本知识。
具体可结合材料中“价格虽然是引导市场资源流向的指挥棒，但当价格信号出现异常波动时，单靠市场自身运作难以尽快修复，需要更好发挥政府的作用”这一关键信息，从发挥市场在资源配置中的决定性
作用，国家实施科学的宏观调控，正确处理政府和市场的关系等方面回答。
答案：市场在资源配置中发挥决定性作用是市场经济的一般规律。
我国价格改革重视发挥市场作用，合理减少政府对资源的直接配置，不断扩大市场形成商品价格的范围；科学的宏观调控是发挥社会主义市场经济体制优势的内在要求，我国价格改革正确处理了政府与市场的关系，完善了价格监管机制，运用经济手段、法律手段、行政手段规范市场秩序，维护公平竞争的市场环境。