问题 填空题

硝酸银容量法测定水样中氯化物时,在滴定反应中,Ag+离子可以和Cl离子作用生成白色AgCl沉淀,也可以和CrO42-离子作用生成红色的Ag2CrO4沉淀。由于(),当AgNO3标准溶液滴加到水样中时,首先生成AgCl的白色沉淀,然后再生成的Ag2CrO4红色沉淀。

答案

参考答案:AgCl的溶解度比Ag2CrO4

阅读理解

阅读理解

     Most people have jobs. They go to work nearly every day. Some people are lucky. Either they have very

interesting jobs or they make a lot of money. Most people are not so lucky. Either their jobs are not very

interesting or they don't make a lot of money.

     The most interesting jobs are often the most difficult. People take a long time to learn how to do them.

Doctors study for at least(至少) six years after finishing school. Airline pilots(航天飞行员) study longer.

Most airline pilots are at least 30 years old.

     Some young people have interesting and well-paid(高收入) jobs. Many successful stars are usually under

35. Older people usually cannot play these sports very well. They cannot move fast enough(足够的). Golf,

however, is good sport for older people. Many successful golfers are quite old.

     Most people work until(直到) they are 60 or 65 years old. Then they retire(退休) and have a lot of free time.

Some people never (从不) retire. These people usually have very interesting jobs. Writers, artists, musicians

and actors usually work until they die. Their work is their life.

1.What kind of jobs do lucky people have?

A. Easy jobs with less(很少) money.

B. Not very interesting jobs.

C. Interesting and good jobs with much money.

D. Difficult jobs with less money

2.Why do some jobs take a long time to learn?

A. Because they are difficult.

B. Because they are well-paid

C. Because they are interesting.

D. Because they are easy.

3. Why are young people successful at sports like tennis?

A. Because they can move fast.

B. Because they don't have to study.

C. Because they get paid a lot of money.

D. Because they can't move fast.

4. Who has to(不得不) retire when he is 60?

A. A writer   B. An actor   C.  A policeman     D.  A musician

5. What does the word "die"mean in Chinese?

A. 喜欢

B. 死亡

C. 想

D. 生病

单项选择题