Question

Put an ice cube from your fridge into a glass of water. You have a piece of string(线) 10 centimeters long. The problem is to take out that piece of ice with the help of the string. But you must not touch the ice with your fingers.
You may ask your friends to try to do that when you are having dinner together. There is a saltcellar on the table. You must use salt when you carry out this experiment.
First you put the string across the piece of ice. Then put some salt on the ice. Salt makes ice melt(融化). The ice round the string will begin to melt. But when it melts, it will lose heat. The cold ice cube will make the salt water freeze(结冰) again.
After a minute or two you may raise the piece of string and with it you will raise your piece of ice!
This experiment can be very useful to you. If, for example, there is ice near the door of your house, you must use very much salt to melt all the ice. If you don’t put enough salt, the water will freeze again

1. 1.
   We must use           when we carry out this experiment
   1. A.
      a fridge
   2. B.
      some food
   3. C.
      a table
   4. D.
      some salt
2. 2.
   How long will it take to carry out this experiment?
   1. A.
      More than three minutes
   2. B.
      Five minutes or two
   3. C.
      Only one minute or two
   4. D.
      About ten minutes
3. 3.
   We can learn something about           from the passage
   1. A.
      physics
   2. B.
      biology
   3. C.
      chemistry
   4. D.
      maths

Answer 1

DCC
试题分析：本文介绍了一个小实验，作者基本上是按照事情的发展顺序进行介绍，阅读中注意序数词的使用。
1.根据You must use salt when you carry out this experiment.可知选D。
2.根据After a minute or two you may raise the piece of string and with it you will raise your piece of ice!描述可知选C。
3.冰融化成水或者水结成冰属于化学变化，故从本文中学到的是化学知识。选C。
考点：关于一个小实验的说明文
点评：本文浅显易懂，各个小题都能在文中找到适当依据。只要认真阅读短文，注意前后联系，就能顺利完成阅读。