A Simple Scientific ExperimentBelow is a

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A Simple Scientific Experiment

Below is a description of a single scientific experiment. It shows us how iron reacts ( 反应) with air and with water.
Aim : To find out if iron rusts( 生锈) (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 ( 铁钉) ; 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)

小题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

小题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

A．①②

B．①③

C．②③

D．②④

小题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

答案

小题1:A

小题2:D

小题3:C

短文属于说明文。这是一个关于铁和水、空气的反应的科学实验。

小题1:细节理解题。这个实验的目的就是提供干燥空气，因此可推测棉花羊毛的作用是吸湿，保持空气干燥。

小题2:细节理解题。从Iron in air-free water这个实验的方法中可知，第二步和第四步就是为了使水中不含有空气。

小题3:细节理解题。通读三个实验可排除A、B、D三项，通过Iron in ordinary water这个实验的结论可知“Iron rusts in ordinary water.”这也是三个实验中唯一使铁生锈的条件。