最新四年级用字母表示数单元测试题

用字母表示数
一、填空（每题2分）
1.学校买来x盒红粉笔，买来白粉笔的盒数是红粉笔的10倍，学校买来
（）盒粉笔；当x=10时，学校买来（）盒粉笔。

2.每袋面粉重a千克，每袋大米重b千克，8袋面粉和5袋大米共重（）千克。

3.李师傅每小时加工40个零件，加工了a小时，一共加工了（）个。

4.小明的妈妈本来有A元，去买黄瓜，黄瓜每千克b元，小明的妈妈买了a千克，小明的妈妈还剩（）元。

5.7袋面粉a千克，12袋面粉（）千克。

二、选择（将正确答案的序号填在括号里）（每题2分）
1、a2与（）相等。

（A）a×2 （B）a＋2 （C）a×a
2、2x一定（）x2。

（A）大于（B）小于（C）等于（D）不能确定
3、丁丁比昕昕小，丁丁今年a岁，昕昕今年b岁，2年后丁丁比昕昕小（）岁。

（A）2 （B）b－a （C）a－b （D）b－a＋2
4、当a=
5、b=4时，ab＋3的值是（）。

（1）5＋4＋3=12 （2）54＋3=57 （3）5×4＋3=23
5、甲数是a，比乙数的4倍少b，乙数是（）。

（1）a÷4－b （2）（a－b）÷4 （3）（a＋b）÷4
三、判断题（每题2分）
1、8×b可以写成8b。

（）
2、x2一定比2x大。

（）
3、m2代表的意义是2个m相乘。

（）
4、光明小学四年级有m人，五年级比四年级的2倍少4人，则五年级的学生有m2—4人（）
5、当a=4时，正方形的面积与周长相等。

（）
四、省略乘号，写出下面各式（每题1分）
5×b= c×a= x×6= t×2= t×t
1×a= x×x= c×1= 12×a= 10×b=
四、用含有字母的式子表示下面各题的数量关系。

（每题4分）
1、比x的5倍多20的数。

2、比x多20的数再除以4。

3、x的8倍比24少多少。

4、正方形的边长是a，分别列出周长与面积的式子。

5、长方形的长是a，宽是b，分别列出周长与面积的式子。

四、根据要求完成下面各题。

（第1、2题12分，第3题16分）
1、青青林场桐树和雪松各x排，已知梧桐树每排12棵，雪松每排14棵
（1）栽梧桐树和雪松共多少棵？
（2）当x=20时，青青林场一共有多少棵梧桐树和雪松？
2、一辆汽车，每小时行驶a千米，上午行驶4小时，下午行驶了b千米。

（1）用式子表示这辆汽车行驶的千米数。

（2）当a=80、b=200时，这辆汽车行驶了多少千米？
3、正方形的边长是a，用两个边长为a的正方形拼成一个长方形
（1）用带有字母的式子表示得到的长方形的周长与面积。

（2）当a=7
识二英语部分
Passage One
Christopher Thomas, 27, was a writer by night and a teacher by day when he noticed he was always tired and was losing weight fast. Diagnosed with diabetes(糖尿病), Thomas would need to inject himself with insulin(胰岛素) three times a day for the rest of his life or risk nerve damage, blindness, and even death. And if
that weren't bad enough, he had no health insurance.
After a month of feeling upset, Thomas decided he'd better find a way to fight back. He left Canton, Michigan for New York, got a job waiting tables, nicknamed himself the Diabetic Rockstar, and created , a free online community for diabetics and their loved ones—a place where over 1,100 people share personal stories, information, and resources.
Jason Swencki’s son, Kody, was diagnosed with type diabetes at six. Father and son visit the online children's forums(论坛) together most evenings. "Kody gets so excited, writing to kids from all over," says Swencki, one of the site's volunteers. "They know what he's going through, so he doesn't feel alone."
Kody is anything but alone: Diabetes is now the seventh leading cause of death in the United States, with 24 million diagnosed cases. And more people are being diagnosed at younger ages.
These days, Thomas's main focus is his charity（慈善机构）, Fight It, which provides medicines and supplies to people—225 to date—who can't afford a diabetic's huge expenses. has raised about $23,000—in products and in cash. In May, Thomas will hold the first annual Diabetic Rockstar Festival in the Caribbean.
Even with a staff of 22 volunteers, Thomas often devotes up to 50 hours a week to his cause, while still doing his full-time job waiting tables. "Of the diabetes charities out there, most are putting money into finding a cure," says Bentley Gubar, one of Rockstar's original members. "But Christopher is the only person I know saying people need help now."
56. Which of the following is true of Christopher Thomas?
A.He needs to go to the doctor every day.
B.He studies the leading cause of diabetes
C.He has a positive attitude to this disease.
D.He encourages diabetics by writing articles.
57. was created for _________.
A. diabetics to communicate
B. volunteers to find jobs
C. children to amuse themselves
D. rock stars to share resources.。