2019北京交大附中初一(上)期中英语含答案
2019北京交大附中初一（上）期中
英语
听后选择
听对话或独白，根据对话或独白的内容，从下列各题所给的 A、B、C 三个选项中选择最佳选项。每段对话或独白你将听两遍。
请听一段对话，完成第 1 至第 2 小题。
1. What is the man doing?
A. Taking a walk.
B. Listening to music.
C. Studying English.
2. When does the woman play tennis?
A. Every Monday.
B. Every Tuesday.
C. Every Thursday.
请听一段对话，完成第 3 至第 4 小题。
3. What does the boy think of math?
A. Boring.
B. Difficult.
C. Interesting.
4. What i s the girl’s favorite subject?
A. Art.
B. Math.
C. Chinese.
请听一段对话，完成第 5 至第 6 小题。
5. Who is the man shopping for?
A. His son.
B. His friend.
C. His daughter.
6. How much will the man pay for the large jacket?
A. $10.
B. $20.
C. $30.
请听一段对话，完成第 7 至第 9 小题。
7. What does Grandma buy online?
A. Food.
B. Books.
C. Drinks.
8. What does Grandma think of using a computer?
A. Easy.
B. Tiring.
C. Exciting.
9. What can we learn about Grandma?
A. She likes getting emails.
B. She never reads news online.
C. She enjoys learning new things.
请听一段独白，完成第 10 至第 12 小题。
10. What do many families enjoy doing in winter?
A. Giving gifts.
B. Cooking dinner.
C. Making snowmen.
11. What does the speaker really want in winter?
A. A white Christmas.
B. A new winter coat.
C. Sweet winter food.
12. What is the speaker mainly talking about?
A. What he wears in winter.
B. Why he loves winter best.
C. How he spends Christmas.
听独白，记录关键信息。独白你将听两遍。
请根据所听到的独白内容和提示词语，将所缺的关键信息填写在答题纸的相应位置上。
知识运用
单项填空
从下面各题所给的 A、B、C、D 四个选项中，选择可以填入空白处的最佳选项。
1.I have a sister. name is Paul.
A. Her
B. His
C. My
D. Your
2.We often play table tennis ______ our friends at school.
A. to
B. of
C. for
D. with
3.There is interesting story book and some pens in my bag.
A. a
B. an
C. the
D. /
4.Sam is not a boy. His things are everywhere in the bedroom.
A. tidy
B. healthy
C. nice
D. dirty
5.— is my watch?
—It’s on the desk.
A. What
B. How
C. Who
D. Where
6.Let’s to invite Lily to have Lunch next Friday.
A. go
B. goes
C. going
D. to go
7.He a sister, but he doesn’t have a brother.
A. have
B. has
C. don’t have
D. doesn’t have
8.—Hello, Tony. I’m Frank.
—
A. How about you?
B. What’s your name?
C. Nice to meet you.
D. You are welcome.
短文填空
阅读下列短文，根据短文内容填空。在未给提示词的空白处仅填写一个适当的单词，在给出提示词的空白处用括号内所给词的正确形式填空。
A
Hi, I’m Jenny. Here are two nice ___9___(photo) of my family. My grandfather and grandmother are in the
___10___(one) photo. These are my parents, Alan and Mary. In the next picture are my brothers, Bob and Eric. These two girls ___11___( be )my sister Cindy and my cousin Helen. Coco is in my ___12___, too.
B
Frank Brown:
I don’t have a soccer ball, ___13___my brother Alan does. We go to the same school and we love soccer. We play it at school with our friends. It’s ___14___(relax).
Gina Smith:
Yes, I do. I have two soccer balls, three volleyballs, four basketballs and five baseballs and bats. I love
___15___(sport), but I don’t play them--I only watch them on TV!
Wang Wei:
No, I don’t. Soccer is difficult. I like ping-pong. It’s easy for me. I have three ping-pong balls and two ping-pong bats. After ___16___, I play ping-pong with my classmates.
完形填空
阅读下面的短文，掌握其大意，然后从短文后各题所给的 A、B、C、D 四个选项中，选择最佳选项。
A beautiful smile
When I was thirteen years old, a girl gave me an important gift. It was a smile.
It was the early autumn of my_____17_____year at a new school. It’s also the first year of middl e school. No one knew me. I was very ___18___, and afraid to make friends with anyone.
Every time I heard the other students talking and laughing, I felt even more lonely. I could not talk to anyone about my problem, and I didn’t want my parents to worry about me.
One day, my classmates were ___19___with their friends, but I sat in silence(沉默) and felt so down that everything didn’t sound real. At that moment, a girl entered the classroom. I did not know who she was. She passed me and then turned back. She looked at me and, without a word,_____20_____.
Suddenly, I felt the ___21___of something bright and friendly. It made me feel happy, lively and warm. It was like a hidden treasure(宝藏).
That smile ___22___my life. I started to talk with other students. Day by day, I learnt to trust people, and they included me in their circle of friends. The girl with the bright smile has become my best friends now, and we stick together like glue.
I can talk to her about my study, feelings and hobbies, pretty much everything. I am so ____23____that I met such a nice girl.
One day, I asked her why she smiled at me that day. She said she could not remember!
Now I believe that the world is like a ___24___. It is just what you think it is. If you think you are lonely, you might always be alone. But if you smile at it, it will always smile back!
17. A. first B. second C. third D. last
18. A. happy B. lonely C. friendly D. excited
19. A. eating B. talking C. drawing D. dancing
20. A. left B. laughed C. played D. smiled
21. A. talk B. surprise C. touch D. experience
22. A. broke B. found C. changed D. hit
23. A. lucky B. relaxed C. interested D. healthy
24. A. lesson B. friend C. game D. mirror
阅读理解
阅读下列短文，根据短文内容，从短文后各题所给的 A、B、C、D 四个选项中，选择最佳选项。
A
Three people from different countries are having a three-week English learning in the United States. In the first class, they are introducing themselves.
25. Chejudo is .
A. a city in Turkey
B. a city in Mexico
C. an island in Korea
D. an island in Turkey
26. Oscar is making a film about .
A. a capital city
B. a family
C. an airplane
D. a pilot
27. What is Pinar's job?
A. She makes films.
B. She flies airplanes.
C. She teaches in a university.
D. She draws pictures for books.
B
The Basket
Two things changed my life; my mother and a white, pretty bike basket. My mother is a strict parent and I had to earn my pocket money by doing housework around the house.
One day, my mother drove me to the bike shop to get a tire fixed, and there it was in the window; white, shiny, and decorated with beautiful flowers. It was so special and I knew I had to have the basket. “It’s beautiful,” my mother said when I pointed it out to her.
“Mom, please, can I get it? I'll do more housework for as long as you say, but I need that basket. I really love it...”
“You know,” she said gently, “If you save up, you could buy this yourself.” “By the time I make enough, it'll be gone!”
“I’ll buy the basket for you, but you have to work for it,” she said.
My mother bought the beautiful basket and put it safely in some secret place I couldn’t find. Each week I eagerly counted my growing income. And then, weeks later, I jumped for joy. Oh, happy day! I made it! I finally had the exact amount we’d agreed upon.
Days later, the unthinkable thing happened. A neighbor girl appeared with the exact same basket on her shiny, new bike. The eight-year-old me cried and ran fast back home to tell my mother about this terrible news.
And then came the lesson I’ve taken with me through my life; "Honey, it doesn't matter that the baskets look the same. Your basket is extra-special," Mom said, gently drying my hot tears. "Your basket is special because you got the basket through your hard work.”
28. The girl’s mother drove her to the bike shop to .
A. get a tire fixed
B. make some money
C. buy a new bike
D. buy a pretty bike basket
29. The girl cried to her mother because .
A. the mother was too strict with her
,
B. she didn't like doing the housework
C. the neighbor girl had the same basket
D. she didn't have the money for the basket
30. According to the passage the basket was special because .
A. it was not only pretty but also not expensive
B. it was different from the neighbor girl’s basket
C. the writer decorated it with beautiful flowers
D. the writer got the basket through her hard work
C
A black hole is a place in outer space with very strong gravity. Gravity is a great force（力量） that shapes the universe. On Earth, gravity makes apples fall from trees. It keeps your feet planted on the ground. The gravity in a black hole is much stronger. It is so strong that nothing around it can get away from it, not even light.
Black holes are invisible. We can’t actually see them because they don't throw back light. But scientists can find them with space telescopes（望远镜）and special tools. The strong gravity makes nearby stars move in a certain way. By studying how the stars move, scientists can find out if they are flying around a black hole. Strange things happen around black holes. This makes black holes a popular subject of science fiction（科幻）stories, although they are very real.
A black hole forms when a star dies. The star falls in on itself and turns into a very small point. Because of its small size and huge mass（质量）, the gravity will be so strong that it will pull light in and become a black hole. Black holes can grow huge as they continue to pull other things in and “eat” them. Many scientists believe that there are super-massive black holes at the center of galaxies, including the Milky Way.
The idea of the black hole was first suggested by two different scientists in the 18th century: John Michelle and Pierre-Simon Lap lace. In 1967, a physicist named John Archibald Wheeler came up with the name “black hole”. Studying black holes can tell us many things about our galaxy and help scientists answer questions about the universe.
31. The word “invisible” in Paragraph 2 probably means “”.
A. far to go
B. impossible to see
C. hard to catch
D. easy to find
32. The third paragraph is mainly about .
A. how big black holes are
B. how heavy black holes are
C. how black holes are formed
D. how black holes “eat” stars
33. From the passage we learn .
A. a star’s moving path can’t help scientists find a black hole
B. writers love writing about black holes because they are real
C. there aren’t any black holes at the center of the Milky Way
D. John Archibald Wheeler came up wi th the name “black hole”
D
Need to buy something? Why go to a store? Buy it on the Internet! Need it now? Why wait? Ask for next-day delivery! Each day, more and more people try online shopping. In fact, online sales have doubled in the last ten years. But not everyone is excited. Some scientists now say that online shopping is bad for the environment.
People are surprised to hear this. “They think, ‘I don’t need to drive, and the business doesn’t need to build a store, so there will be less pollution,’” says Nuria Prost, an environmental scientist. “But it is not so simple. In fact, online shopping is wasteful. It also adds to air pollution.”
In truth, the Internet is not always as good a friend to the environment as it seems. For example, most people thought that the Internet would help offices use less paper and other materials. But paper use increased by 33 percent between 1986 and 1997. “Online shopping could have similarly negative effects,” says Nevil Cohen, a professor of environmental science.
Part of the problem is what people are buying these days. In the past, people bought things on the Internet that did not require much packing material, such as books and clothing. But now people also shop online for large, heavy products such as televisions, computers, and furniture. These products need to be packed in large amounts of plastic and paper. This creates a lot of waste.
Another problem caused by online shopping is air pollution. When customers buy products and ask for next-day delivery, companies often have to send them by air. Airplanes use much more fuel than cars and produce more carbon dioxide (CO2). When people buy a lot of different things from different online businesses, this creates even more travel by airplane.
Online product returns are also a problem. For example, an online shoe store may allow customers to return shoes without extra pay if they are the wrong size. This doubles the packing material and number of airplane trips required to sell one pair of shoes.
“If people want to protect the environment they need to think before they shop,” says Prost. “People need to ask
themselves: Is this exactly what I want? Do I really need it tomorrow, or can I wait?” Online stores can also charge（收费）customers for returns. This may make people shop more carefully. “Online shopping is fast and easy,” says Prost, “but we can’t forget the negative effects it has on the environment.”
34. Prost probably agrees that .
A. people should drive to stores to buy things ,
B. people can buy things online without careful consideration
C. online shopping saves more than shopping in a store
D. online shopping adds pollution to the environment
35. What do companies do to meet the needs of the next-day delivery?
A. Prepare more products.
B. Send the products by air. .
C. Get more workers to pack.
D. Open more stores in cities.
36. What is probably the best title of the passage?
A. A Cleaner Way to Shop?
B. A Different Lifestyle to Keep?
C. A Good Deal to Make?
D. A New Business to Start?
阅读短文，根据短文内容回答问题。
Everybody knows that soccer is one of the most popular sports in the world.
Soccer is not a new sport. People all over the world played the game in different ways long ago. For example, in China nearly 2, 000 years ago, soldiers kicked a ball as part of their exercise. Five hundred years ago in Europe, games in the street were common.
Soccer became popular in England in the 1800s. Different schools, clubs and groups played with different rules. In 1863, these English groups had meetings. They organized （组织） the different games into one game with similar rules. Soon, they formed the Football Association.
Not everyone agreed with the new rules. In England, some groups wanted to hold the ball with their hands so these groups formed rugby clubs. Groups in the United States also wanted to use their hands in the sport so they formed “football” clubs. Americans who didn’t want to use their hands called the game “soccer”. Soccer is a short form of the word association.
From England, soccer began to grow. The first official international game of soccer was played between Scotland and England in 1872. By the 1880s, there were professional soccer teams in several parts of Europe. English players also introduced soccer to Africa, South America and New Zealand.
Soccer soon became very popular all around the world. FIFA, the international football federation（联盟）, met for the first time in 1904. Seven countries came to the meeting. The first World Cup was in Uruguay in 1930. Only 13 countries played in the Uruguayan World Cup.
The World Cup is now the most popular sporting event in the world. Over 720 million people around the world watch the final game of the World Cup.
Next time you’re playing soccer with your friends, remember that you’re part of a long history of a f un and exciting sport.
37. Is soccer a new sport?
________________________________________________________________________________________________ ____________________________________________________
38. Why did people form "football" clubs in America?
________________________________________________________________________________________________ ____________________________________________________
39. When was the first official international game of soccer?
________________________________________________________________________________________________ ____________________________________________________
40. How many people around the world watch the final game of the World Cup?
________________________________________________________________________________________________ ____________________________________________________
书面表达
.完成句子
根据下面各题所给的中文及英文提示，完成下面的句子。
41. —他叫什么名?
—他是迈克˙米勒。
—_____is_____name?
—He is Mike Miller.
42. 那两个男孩是我的哥哥。
_____two boys are my_____
43. 请打电话给她，号码是 68902909。
Please_____her_____68902909.
44. 如果你有问题，可以向老师求助。
You can_____the teacher_____help if you have problems.
45. 放学后去踢足球听起来很好。
Playing soccer after school_____.
文段表达
46.根据中文和英文提示，写一封意思连贯、符合逻辑、不少于 50 词的回信。信的开头和结尾已给出，其词数不计入所要完成的回信内。所给英文提示词语仅供选用。请不要写出你的校名和姓名。
学校的体育俱乐部（sports club）正在招募会员，你想参加这次活动。假如你叫李华，
请你写一篇不少于 50 词的短文介绍一下你的个人情况，包括你的名字，联系电话，喜欢哪些学科，哪个运动项目及原因。
提示词语：sports club, member, name, telephone number, basketball, relaxing
Dear President,
I want to join the school sports club and become the member of it.
I’m looking forward to your reply.
Yours,
Li Hua
2019北京交大附中初一（上）期中英语
参考答案
知识运用
单项填空
从下面各题所给的 A、B、C、D 四个选项中，选择可以填入空白处的最佳选项。
1.【答案】A
2.【答案】D
3.【答案】B
4.【答案】A
5.【答案】D
【解析】
6.【答案】A
7.【答案】B
8.【答案】C
A
【答案】9. photos
10. first 11. are
12. family
B
【答案】13. but
14. relaxing
15. sports 16. class
【答案】17. A 18. B 19. B 20. D 21. C 22. C 23. A 24. D
【解析】
本文讲述的是同学的微笑改变了作者的一切的故事。新到一所学校后，作者没有朋友，感到孤独。班上一个女孩的微笑使得他开始同别的同学交谈，交上了新的朋友。世界就像一面镜子，你认为它是怎样的，他就是你认为的那样。你对它微笑，它也总是对你微笑。
【17题详解】
句意：是我在新学校的第一个秋季。
A. first第一；
B. second第二；
C. third第三；
D. last最后的；由下文：是我中学的第一年，没有人认识我，可知：这是作者第一学年的秋天。故选A。
【18题详解】
句意：我非常孤独并且害怕和任何人交朋友。
A. happy高兴的；
B. lonely 孤独的；
C. friendly友好的；
D. excited激动的。由上句，没有人认识我，因此我很孤独。故选B。
【19题详解】
句意：一天，我的同学们在和他们的朋友们说话。
A. eating吃东西；
B. talking 说话；
C. drawing画画；
D. dancing跳舞。由下文可知，当时是在教室里，令我感到更加孤独的活动，可以推测出是“说话，交谈”。故选B。
【20题详解】
句意：她看着我，一个字也没有说，微笑着。
A. left离开；
B. laughed笑；
C. played 玩耍；
D. smiled微笑。由下文可知，女孩对我微笑了。故选D。
【21题详解】
句意：突然，我感到了什么明亮的、友好的感触。
A. talk说话，交谈；
B. surprise诧异，惊奇；
C. touch触摸，感触；
D. experience经历，体验。这里表达的是我有了使我开心的感触。故选C。
【22题详解】
句意：微笑改变了我的生活。
A. broke打破；
B. found找到；
C. changed改变；
D. hit打，撞击；根据下文，从那以后，作者变了，不再孤独。因此选C。
【23题详解】
句意：我很幸运遇到了这么好的女孩。
A. 幸运的；
B. 放松的；
C. 有趣的；
D. 健康的；根据句意理解可知，这里表达的是遇见女孩很幸运，所以这里选择A。
【24题详解】
句意：现在，我相信这个世界就像一面镜子。
A. lesson功课、教训；
B. friend朋友；
C. game游戏；
D. mirror镜子。由下文，你是怎样认为的，世界就是那样的，你对它微笑，它也对你微笑。就像镜子一样。故选D。
阅读理解
阅读下列短文，根据短文内容，从短文后各题所给的 A、B、C、D 四个选项中，选择最佳选项。
A
【答案】25. C 26. B 27. B
【解析】
本文是关于三个人分别作的自我介绍。
【25题详解】
细节理解题。根据PakJee-Eun描述中的“My family is in Chejudo, a large island in Korea.”可知，Chejudo是韩国的一个很大的岛屿，故答案为C。
【26题详解】
细节理解题。根据Oscar描述中的“Right now, I am making a film about a family in Guadalajara.”可知，他正在拍一部关于一家人的电影，故答案为B。
【27题详解】
细节理解题。根据Pinar描述中的“I fly airplanes for a small company.”可知，她的工作是开飞机，故答案为B。
B
【答案】28. A 29. C 30. D
【解析】
本文为一篇记叙文。作者回忆自己母亲对孩子不寻常的教育方法。通过一个自行车篮子的事情，母亲教会作者什么事情都要自力更生，通过自己努力得到的东西才是珍贵的。
【28题详解】
细节理解题。根据第二段的第一句my mother drove me to the bike shop to get a tire fixed可知妈妈带女孩去单车店是为了修轮胎，所以本题选择A。
【29题详解】
细节理解题。根据第七段A neighbor girl appeared with the exact same basket on her shiny, new bike. The eight-year-old me cried and ran fast back home to tell my mother about this terrible news.可知“我”向母亲哭诉是因为隔壁家的女孩有一个一模一样的车篮子，所以本题选择C。
【30题详解】
细节理解题。根据文章最后一段的最后一句Your basket is special because you got the basket through your hard work 可知车篮子之所以特别是因为作者是通过自己的努力得到的。
C
【答案】31. B 32. C 33. D
【解析】
短文介绍了黑洞的定义、形式和可能的形成原因，由于黑洞没有光线发射出来因而肉眼不可见，科学家在试图使用卫星和望远镜对其进行研究。
【31题详解】
词义猜测题。根据文中We can’t actually see them because they don't throw back light.我们看不到他们，因为他们不反光。可知，这里选择B。
【32题详解】
段意概括题。根据第三段首句A black hole forms when a star dies.恒星死后形成黑洞。以及后文中的内容可知，主要是介绍黑洞是如何形成的，所以应该选择C。
【33题详解】
细节理解题。根据文中In 1967, a physicist named John Archibald Wheeler came up with the name “black hole”.1967年，物理学家约翰·阿奇博尔德·惠勒提出了“黑洞”这个名字。可知，本题应该选择D。
D
【答案】34. D 35. B 36. A
【解析】
这篇文章主要介绍了越来越多的人尝试网上购物。事实上，网上销售在过去的十年里翻了一番。但并不是每个人都很兴奋，一些科学家现在认为，网上购物对环境有害，人们听到这个很惊讶，他们认为不需要开车，业务交易不需要建立一个商店，所以将会有更少的污染，环境科学家努力亚说道：“但这并不是那么简单。事实上，网上购物是浪费，它也增加了空气污染。”事实上，互联网并不总是看起来对环境那么好。网上购物方便快捷，但是我们不能忘记对环境的负面影响。
【34题详解】
细节理解题。根据“Online shopping is fast and easy, “says Prost,” but we can’t forget the negative
effe cts it has on the environment.”“网上购物方便快捷”普罗斯特说，“但是我们不能忘记对环境的负面影响。”可知Prost认为网购会增加环境污染。故选D。
【35题详解】
细节理解题。根据When customers buy products and ask for next-day delivery, companies often have to send them by air.当顾客购买产品，要求第二天交货，公司往往通过空运发送它们。故选B。
【36题详解】
最佳标题题。整篇文章主要介绍了网购其实没有使环境保护和清洁，反而增加环境污染，对环境造成一定的影响，所以标题应该是网购真的是一种清洁的购物方式吗？故选A。
阅读短文，根据短文内容回答问题。
【答案】37. No, it isn't.
38. Because they wanted to use their hands in the sport.
39. In 1872.
40. Over 720 million people.
【解析】
本文主要讲述了足球的这项运动不同国家的不同规则以及发展和世界杯的成立等相关信息。
【37题详解】
细节理解题。根据文中Soccer is not a new sport可知，本题填No, it isn't.。
【38题详解】
细节理解题。根据文中Groups in the United States also wanted to use their hands in the sport so they formed “football” clubs.美国的团体也希望在这项运动中使用他们的手，所以他们成立了“足球”俱乐部。可知本题填Because they wanted to use their hands in the sport.。
【39题详解】
细节理解题。根据文中The first official international game of soccer was played between Scotland and England in 1872.第一场正式的国际足球比赛于1872年在苏格兰和英格兰之间进行。可知，本题填in 1872。
【40题详解】
细节理解题。根据文中Over 720 million people around the world watch the final game of the World Cup.全世界超过7.2亿人观看了世界杯的决赛。可知。本题填over 720 million people。
书面表达
完成句子
根据下面各题所给的中文及英文提示，完成下面的句子。
【答案】41. (1). what (2). his
42. (1). Those (2). brothers
43. (1). call (2). at
44. (1). ask (2). for
45. sounds great
【解析】
【41题详解】
根据中英文对照可知，这里缺少什么和他的，英语中什么是疑问词what，他的名字，英语中表达为his name，空格后是名词，所以这里填形容词性物主代词，所以填his，所以本题填what，his。
【42题详解】
根据中英文对照可知，这里缺少的是那和哥哥，英语中那个是that，是单数，但是文中two boys，所以这里应该填that的复数those，而既然是两个男孩，所以兄弟要用复数形式，所以应该填brothers，所以这里those，brothers。
【43题详解】
根据中英文对照可知，这里缺少的是打电话给某人，英语中打电话给某人是一个固定的短语，call sb at，本题是祈使句，please后面接动词原形，所以直接填call，at。
【44题详解】
根据中英文对照可知，这里缺的是向某人求助，英语当中是一个固定的短语ask sb for help，本题中can是情态动词，后面要接动词原形，所以填ask，for。
【45题详解】
根据中英文对照可知，这里缺少的是听起来很好，英语中听起来是sound，好的是good/ great，而本题中主语是踢足球这件事情，所以动词要用三单的形式，所以填sounds，所以这里填sounds great。
文段表达
46.【答案】Dear President,
I want to join the school sports club and become the member of it.
My name is Li Hua. I am 12 years old this year. I study in No. 5 Middle School. My telephone number is 57824361. I like playing sports because I think playing sports can make me relaxing. My favourite sport is playing basketball and I have two basketballs. I often play basketball with my friends after school。I am good at English. I think it is interesting. I can sing English songs well. I am eager to join the sports club.
I’m looking forward to your reply.
Yours,
Li Hua 【解析】
【详解】1. 题干解读：这是一篇列图表作文，也是一篇提纲作文。要根据提示信息审清题意，正确运用人称和时态，在介绍自己想加入健康体育俱乐部时，可使用第一人称；时态主要以一般现在时为主。表格信息全部要写进作文里，也可适当进行拓展发挥，可以结合自己的生活实际进行拓宽。
2. 例文解读：文章语言结构比较清晰，语言应用简单，词汇应用较娴熟，使用简单的语言把题目要求表述的完整清楚。
3. 高分亮点：
短语：sport club；play … with；after school；be good at；be eager to。
句型：because引导原因状语从句；and引导的并列句；I think＋宾语从句。