Question

A Simple Scientific Experiment
Below is a description of a single scientific experiment. It shows us how iron reacts ( 反應) 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 : 3 clean iron nails ( 鐵釘) ; test tubes ; 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.
Iron in air-free water
Method
(1)Half-fill a test tube with water.
(2)Boil the water for three minutes. (This makes sure there is no air in the water.
(3)Put two or three clean nails in the water.
(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.
Conclusion
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)

1. 1.
   In the first part of the experiment the cotton wool is most probably used to ______________.
   1. A.
      keep the air dry
   2. B.
      keep the tube wet
   3. C.
      make the nails rust
   4. D.
      keep the tube clean
2. 2.
   What are necessary steps to make sure the water in the tube is air free?
   ①Leave half a tube of water in it              
   ②Boil the water for some time
   ③Put some clean iron nails in the tube           
   ④Add some oil to the water
   1. A.
      ①②
   2. B.
      ①③
   3. C.
      ②③
   4. D.
      ②④
3. 3.
   We can conclude from the experiment that only ____________ makes iron rusty.
   1. A.
      dry air
   2. B.
      cotton wool
   3. C.
      ordinary water
   4. D.
      air-free water

Answer 1

ADC
短文屬于說明文。這是一個關(guān)于鐵和水、空氣的反應的科學實驗。
1.細節(jié)理解題。這個實驗的目的就是提供干燥空氣，因此可推測棉花羊毛的作用是吸濕，保持空氣干燥。
2.細節(jié)理解題。從Iron in air-free water這個實驗的方法中可知，第二步和第四步就是為了使水中不含有空氣。
3.細節(jié)理解題。通讀三個實驗可排除A、B、D三項，通過Iron in ordinary water這個實驗的結(jié)論可知“Iron rusts in ordinary water.”這也是三個實驗中唯一使鐵生銹的條件。