问题 单项选择题

化学通式为R1X1R2X2的捕收剂,如十六烷基胺二酯酸,其属于()。

A、阳离子型捕收剂

B、阴离子型捕收剂

C、非离子型捕收剂

D、多极(两性)捕收剂

答案

参考答案:D

阅读理解

阅读理解。

     People say bees can always find the way home. Wherever you put them, they can come back. John

 Smith didn't believe this, so he did an experiment (实验).

     He caught 20 bees under the eave (屋檐) of his house and put them in a bag. He asked his daughter to

  wait there and see if the bees would come back. He marked (作标记) the bees and took them two

 miles away. Then he opened the bag and let the bees out.

     When he got home, his daughter ran to him and shouted, " Two bees have come back." Both John and

  his daughter were very excited. He went to see them at once. Yes, two bees were there. They flew about

  two miles in three quarters. And they came back with pollen (花粉) on their bodies. It was getting dark.

  No more bees came back home. John became worried.

      The next morning, he came to see the bees again. To his surprise, another fifteen bees came back with

  pollen on their bodies. As a result, John believed that bees really have the ability of finding their way

 home.

1.  John Smith caught the bees because he wanted to find _____.

    A. how bees build their own home

    B. when bees usually look for their food

    C how bees talk with each other

    D. if bees can find their way home

2. John Smith let out the bees _____.

    A. in the garden behind his house        

    B. under the eave of his house

    C. on the roof (屋顶) of his house        

    D. two miles away from his house

3. The first two bees spent _____ flying back to John's house. 

    A. ten minutes    

    B. half an hour    

    C. forty-five minutes    

    D. one hour

4. _____ bees in all were back until the next morning. 

    A. 2            

    B. 15            

    C. 17                

    D. 20

单项选择题