问题 填空题

已知A、B、C三种纯净物均含有氧元素,而且它们在一定条件下有下列化学反应中转化关系:A可生成B,A也可生成C,B可生成C,你认为A、B、C可以是你熟悉的哪三种物质,写化学式A______  B______.

答案

A、B、C净物均含有氧元素,可假设A为过氧化氢,过氧化氢在二氧化锰的催化剂下生成水和氧气,水电解生成氢气和氧气,所以B为水,C为氧气,带入验证符合题中转化关系.

故答案为:H2O2,H2O.

阅读理解

阅读理解

     There are many American expressions about insects-like bees, for example. Bees always appear

to be busy, moving around their homes, or hives. In fact, you might say your house was a beehive of

activity if your whole family was helping you clean. You also might say you made a beeline for

something if you went there right away.

     Here is an expression about bees that is not used much any more, but we like it anyway. We think

it was first used in the nineteen twenties. If something was the best of its kind, you might say it was the

bee's knees. Now, we admit that we do not know how this expression developed. In fact, we do not

even know if bees have knees!

     If your friend cannot stop talking about something because she thinks it is important, you might say

she has a bee in her bonnet. If someone asks you a personal question, you might say "that is none of

your beeswax". This means none of your business.

     Speaking of personal questions, there is an expression people sometimes use when their children

ask, "where do babies come from?" Parents who discuss sex and reproduction say this is talking about

the birds and the bees.

     Hornets are beelike insects that sometimes attack people. If you are really angry, you might say you

are mad as a hornet.

     Butterflies are beautiful insects, but you would not want to have butterflies in your stomach. That

means to be nervous about having to do something, like speaking in front of a crowd. You would also

not want to have ants in your pants. That is, to be restless and unable to sit still.

1. When Tom spends his weekend cleaning his house, we can say he is as busy as ________.

A. an insect              

B. a hornet              

C. a butterfly                

D. a bee

2. Which of the following expressions can NOT be often heard in daily life?  

A. Make a beeline.

B. That is none of your beeswax.

C. It's the bee's knees.

D. My house is a beehive of activity.

3. When you say to Mary "you have a bee in your bonnet", what do you really mean?

A. She should stop talking about something.

B. You care about her very much.

C. She is in danger and needs help.

D. What she talks about is really important

4. Which of the following would be discussed next?   

A. Some expressions about pigs.

B. Some expressions about noses.

C. Some expressions about bugs.

D. Some expressions about colours.

单项选择题