《2025年暑假作业延边教育出版社七年级B版数学华师大版英语仁爱版河南专版》

Ⅷ.趣味小实验
Surprise others with this great trick(技巧)!
This is a fun science trick. You can show it to your family and friends. All you need is some water, a bowl, some pepper(胡椒) and some liquid soap(洗洁精).
Here is what to do:
●Put some water in the bowl.
●Put some pepper in the bowl. The pepper will float(漂浮) on top of the water. It does not fall to the bottom of the bowl. Use enough pepper to cover(覆盖) the water.
●Place the tip of your finger(指尖) in the water. Nothing happens.
●Now, put a bit of liquid soap on your finger.
●Place the tip of your finger in the water again. This time, the pepper should move quickly to the sides of the bowl. It looks like the pepper is afraid of the soap!
Try again!
What happens if you try using other materials(材料), such as milk or lemon juice? Find out! Start with a new bowl and put some water and pepper in it, just like you did before. Now, put some lemon juice on your finger. When you place your finger in the water, the pepper should not move. Try again with milk. The pepper should stay where it is again. The trick only works with soap!
Choose the answer:
()61. What do you put in the bowl first?
A. Pepper.
B. Water.
C. Liquid soap.
()62. What happens to the pepper when you put it into the water?
A. The pepper stays on top of the water.
B. The pepper falls to the bottom of the bowl.
C. The pepper moves to the center of the bowl.
()63. What happens when you touch the water with liquid soap on your finger?
A. Nothing happens to the pepper.
B. The pepper falls to the bottom of the bowl.
C. The pepper moves to the sides of the bowl.

答案： 61. B；62. A；63. C