10．Solid passes sound very well．Try holding a wooden stick against part of a machine，and place your ears against the stick．The movement of the ball-bearings（滚珠轴承） can be clearly heard．This is a good way of finding the exact source of trouble in a motorcar engine which sounds as if it is wrong and yet gives no information of where the trouble is．
It is probably a good thing that sound cannot travel through a vacuum（真空），for we are thus limited to earth-made sounds．The violent disturbances which are seen sometimes in the sun，for example，may affect our magnetism（磁力） and our radio．They do not affect our ears，which is a very good thing for our peace of mind．
If we have used our eyes and ears，we may have realized that sound takes time to travel through the air．The sound of thunder nearly always follows the lightning flash although they happen at exactly the same time．And the appearance of white cloud above a distant ship or train tells us，before anything is heard，that its whistle has sounded．Just how fast does sound travel through the air？
The speed of sound in the air at ordinary temperature is about 100feet per second，which is about one mile in five seconds or about 700miles per hour．The speed of sound increases slightly with a rise in temperature and falls with a decrease in temperature； it is not affected by the pressure of the air．
24．We never hear anything that happens on the sunA．
A．because of the vacuum between the earth and the sun
B．because we are only used to earth-made sound
C．because of the distance between the earth and the sun
D．because we are likely to enjoy our peace of mind
25．According to the passage，how fast does sound travel through the air at ordinary temperature？C
A．About 700meters per minute．
B．About 1，100miles per hour．
C．About 60，000feet per minute．
D．About one kilometer in five seconds．
26．How do temperature and pressure affect the speed of sound？D
A．The speed of sound increase with a rise in pressure．
B．The speed of sound decrease with a rise in temperature．
C．The speed of sound increase in lower temperature and greater pressure．
D．The speed of sound decreases with a fall in temperature．
27．The underlined sentence in the second paragraph means"D"．
A．thus we can hear anything but the sound made by the earth
B．we can thus hear the sound from both the earth and space
C．thus we can hardly hear any sound because of the limit of the earth
D．thus we can only hear the sound made on the earth，not the sound coming from the outside．
分析 文章讲述了声音在空气中的传播是受温度的 影响的，随着温度上升而增加，温度降低而减少，但在真空中是不能传播的．
解答 24-27 ACDD
24．A 推理题．根据It is probably a good thing that sound cannot travel through a vacuum（真空），这句话可知，声音不能通过真空传播，故有些东西是听不到的，故选A．
25．C 细节题．通过文章The speed of sound in the air at ordinary temperature is about 100feet per second可知，声音在空气中每秒100英尺，故每分钟传播60，000feet，故选C．
26．D 推理题．根据最后一段The speed of sound increases slightly with a rise in temperature and falls with a decrease in temperature声音传播的速度随着温度的增加而增加，相反，随着温度下降而降低，故选D．
27．D 推理题．根据前面的句子It is probably a good thing that sound cannot travel through a vacuum可知，在真空中声音不能传播，所有我们只能听到地球上的声音，故选D．
点评 本文是人生感悟类阅读理解．这类题材是高考常考的内容，它注重考查考生整体理解文章大意的能力，在做题时要结合题干以及上下文做出正确的选择．
