Question

【題目】

Below is a description of a single scientific experiment. It shows us how iron reacts (反應(yīng)) with air and with water. Aim: To find out if iron rusts(生銹) (a) in dry air; (b) in water that has no air in it (air-free water) ; (c) in ordinary water. Materials: Some clean iron nails (鐵釘) ; test tubes(試管); test tube holder; cotton wool; oil; Bunsen burner.
Iron in dry air Method (1) Put some iron nails at the bottom of a test tube. (2) Push some cotton wool down the tube. (3) Leave the tube for one week. Result After one week, the nails have not rusted. Conclusion Iron does not rust in dry air.	(4) Add some oil to the water. (This will keep air out of the water.) (5) Leave the tube for one week. Result The nails do not rust in the tube with air-free water. Conculsion Iron does not rust in air-free water.
	Iron in ordinary water Method (1) Half –fill a test tube with water and add two or three clean nails. (2) Leave the tube for one week. Result The nails rust in the tube with ordinary water. Conclusion Iron rusts in ordinary water. (238 words)
Iron in air-free water Method (1) Half-fill a test tube with water. (2) Boil the water for three minutes. (This makes surethere is no air in the water.) (3) Put two or three clean nails in the water.

【1】In the first part of the experiment the cotton wool is most probably used to ____.

A. keep the air dry B. keep the tube wet

C. make the nails rust D. keep the tube clean

【2】What are necessary steps to make sure the water in the tube is air-free?

① Leave half a tube of water in it.

② Boil the water for some time.

③ Put some clean iron nails in the tube.

④ Add some oil to the water.

A. ①② B. ①③ C. ②③ D. ②④

【3】We can conclude from the experiment that only ____ makes iron rusty.

A. dry air B. cotton wool

C. ordinary water D. air-free water

Answer 1

【答案】

【1】A

【2】D

【3】C

【解析】

試題分析：本篇文章介紹了鐵在干燥的空氣里，在沒有空氣的水里和普通的水里，鐵是不是會(huì)生銹的幾個(gè)試驗(yàn)。

【1】A細(xì)節(jié)理解題。根據(jù)Push some cotton wool down the tube.可知在試管下面放一些原棉，目的是為了叫空氣干燥。故選A。

【2】C細(xì)節(jié)理解題。根據(jù)Boil the water for three minutes. (This makes sure there is no air in the water.)和Add some oil to the water. (This will keep air out of the water.)可知把試管放煤氣燈下煮幾分鐘（保證水里沒有空氣）和在水里加入適量的油（保證空氣不進(jìn)入到水里）。故選C。

【3】B細(xì)節(jié)理解題。根據(jù)Conclusion Iron rusts in ordinary water.可知鐵只有在普通的水里才會(huì)生銹。故選B。