题目内容
Amazing chemistry experiment (化学实验)
Things you need: a cup some water ice cube (小方冰块) string (线) salt
Steps:
Firstly, fill a cup with water. Put an ice cube into the water.
Secondly, carefully put the string so that it lies(躺)on the top of the ice cube.
Thirdly, when the string touches (接触) the ice cube, ask your friend to add some salt on the ice cube.
Finally, wait for one minute. Then carefully lift(提)the ice cube from the water by picking up the string.
Why does it happen?
Salt can make ice melt (融化). Adding some salt on the ice cube makes a little puddle (水坑) of melted ice. While you wait, the ice cube freezes (凝固) the puddle around the string. Now the ice cube “sticks to” the string so you can lift up(提起)the ice cube.
1.Which of the following things don’t you need in this experiment?
A.knife B.water C.string
2.What do you need to add to the ice cube in this experiment?
A.water. B.salt. C.air.
3.The underlined(划线的) phrase “sticks to” means “ ” in Chinese.
A.碰到 B.分离 C.粘住
4.Which of the following is TRUE?
A.Salt can’t make ice melt.
B.You should put the string into the water.
C.You should add some salt on the ice cube.