单选题   Complete silence is found only in laboratories called anechoic rooms. The wails and ceilings, made of blocks of special sound-sucking materials, are more than three feet thick, while floor coverings are six-foot layers of feathers or cotton wool. Silence here can be as painful to the ears as the din (continuous loud noise) of a steelworks or a rocket blast-off, yet scientists get used to this and stay in these silent rooms for hours at a time, using microphones and electronic equipment to test the various materials being developed to make the world a less noisy place.
    Architects have used scientific discoveries to solve noise problems in a number of ways. Walls are hollowed (having empty space inside) and then filled with sound-sucking materials similar to cotton wool. Extra-thick carpets cover the floors, and thick woolen curtains cover the windows. Air conditioning and heating channels are made less noisy by sound-sucking materials.
    Unfortunately, these techniques and others often work too well in some buildings. Noise-proof rooms become almost anechoic and people living in them are disturbed by the lack of sound. One way of handling this problem is to use what they call 'sound perfume'—artificial (similarly produced, made by man) noise is piped to rooms through small loudspeakers.
单选题     Scientists use anechoic room for ______.
 
【正确答案】 C
【答案解析】 科学家用消声室来______。细节题。从第一段最后一句话可以看出，科学家在消声室里测试各种各样的、可以降低噪音的材料。故答案为C。
单选题     The writer implies that ______.
 
【正确答案】 B
【答案解析】 作者暗示______。推理题。原文第一段中说“这种安静对于耳朵来说不亚于钢厂里或火箭发射时发出的巨大噪音”，可以想象在这样的环境里做实验是很恐怖的事情。故答案为B。
单选题     People suffer in anechoic rooms probably because ______.
 
【正确答案】 B
【答案解析】 人们在消声室觉得很痛苦可能是因为______。推理题。文章第三段讲到，“听觉香水”——人工噪音可以解决人们在几乎完全无声的环境中很痛苦的问题，可以推测出，人们在消声室里不舒服是因为不习惯周围没有一点噪音。故答案为B。
单选题     The article suggests that ______.
 
【正确答案】 A
【答案解析】 文章暗示______。最后一段中提到，因为某些大楼里降噪的效果太好，人们反而因为缺乏声音而不舒服，这时候需要使用扬声器将声音传输到房间里。故答案为A。