Question

    An INTERESTING experiment

It takes a little skill to do this experiment, but the result is truly SURPRISING.

What do you need? Several rubber balloons Wooden skewer（木签） Vegetable oil Paper towel		Step l Blow up a balloon, let some of the air out of it, and tie it closed.
	Step 2 Rub some oil on skewer with paper towel.
	Step 3 Gentle twist（搓捻）and push skewer into end of balloon opposite the knot. If balloon pops（爆 炸），go back to Step 1.
	Step 4 When skewer is in balloon, slowly twist and push it out of balloon near knot.
What will happen?		28    The balloon does not pop, even though it has a skewer in it.
Why won't it pop?	Rubber is made out of long chains of molecules （分子）. The skewer pushes these molecules aside. The molecules mix with the oil and they stick together tightly. The oil on the skewer seals the hole and air cannot get out.

1.Which is the most suitable word for 28 ?

A.Topic B.Result C.Problem D.Reason

2.What’s the proper meaning of the underlined word "seals"？

A.密封 B.润滑 C.点燃 D.腐蚀

3.What can we infer（推断）from the passage?

A.It's easy to push a skewer into and out of a balloon.

B.You'd better blow as much air as possible into a balloon.

C.There's no need for you to use the oil while doing the experiment.

D.It's hard for the air to get out of the hole as molecules and oil stick together.

Answer

1.B

2.A

3.D

【解析】

本篇介绍“气球不爆裂”这个实验所需的器材、实验的步骤、实验的结果并分析原因——长链分子与油混合在一起并紧紧地粘在一起，堵住了洞口，气球才不会漏气。

1.

推理判断题。根据文中“The balloon does not pop, even though it has a skewer in it.” ——即使气球里面有一根木签也不爆裂；可知这句是实验的结果，故选B。

2.

词义猜测题。由实验结果可知，即使气球里有一根木签，也不会爆裂；根据“Rubber is made out of long chains of molecules. The skewer pushes these molecules aside. The molecules mix with the oil and they stick together tightly.”——解释气球不爆裂的原因是长链分子与油混合在一起并紧紧地粘在一起，封住了洞口，气球才不会漏气；故选A。

3.

推理判断题。根据文中“The molecules mix with the oil and they stick together tightly. The oil on the skewer seals the hole and air cannot get out.”可知由于分子和油粘在一起，空气很难从洞里出来，故选D。