刘宇测得深吸气、深呼气、平静吸气、平静呼气时胸围值分别为92厘米、82厘米、90厘米、86厘米，则他的胸围差是（ ）
A．10厘米
B．8厘米
C．4厘米
D．6厘米
胸围差的测量方法是：先让受测者尽力深吸气，记录下吸气终了时的胸围长度，然后，再让受测者尽力深呼气，记录下呼气终了时的胸围长度，计算两次胸围长度之间的差值，即为胸围差数值；因此该同学的胸围差是92cm-82cm=10cm．
故选：A
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| The War Against Sand Imagine living on the edge of a vast desert, which is moving quietly closer to your village every day and covering your fields. The desert is on the move. This is called desertification. Desertification occurs in regions close to an already existing desert. 1 The first is over-use of water in the area. There is not enough water in any case, and if it is not carefully used, disaster can follow. As time goes on, water shortages make farming more and more difficult. In some places, locals can remember local lakes and marshes which were once the homes for all kinds of fish and birds. 2 Farmers leave the land, and fields are replaced by deserts. The second cause is misuse or over-use of the land. 3 Ploughing(耕) large fields and removing bushes and trees means that the wind will blow away the soil. Once the soil is lost, it is hard to replace, and if there is rain, it has nowhere to go, and brings no benefit. 4 Every spring, the skies over some of eastern cities, thousands of kilometers away from the deserts, can be darkened by sandstorms. Dust from deserts can have a great effect on weather systems. While desertification is perhaps being partly caused by global warming, these sandstorms can make global warming worse by adding to what is known as the greenhouse effect. What can be done to slow down or stop the process of desertification? A great deal of work is already under way. Obviously first steps are to find new water sources. 5 Some types of grass also hold the soil together, and stop the wind taking it. Without these efforts, it will be harder and harder to stop the world's deserts in their tracks, and more and more farmers will give up and head for cities. The lesson to be learnt lies beneath the sand. | |
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