压扩器的作用是将话音信号的()进行压缩扩张,达到改善话音通路信杂比的目的。
A.频率范围
B.动态范围
C.响度范围
D.清晰度
参考答案:B
Americans use more water than any other people in the world. If we continue to use water at the rate we do now, we will soon not have enough to meet our needs. In 1980, 40 billion gallons were used each day in the United States. In 1990, 700 billion gallons were used. The average Americans uses almost 90 gallons of water a day for personal use. And much move water is needed to make the things American people like to have. For example, it takes thousands of gallons of water to make one pound of beef for the dinner table. It takes more than 100,000 gallons of water to make a car. If we include these uses of water, the average American uses about 2000 gallons of water a day.
Which is not true according to the passage
A.Americans may run short of water in the future.
B.Americans use more water than ever.
C.Americans use as much water as they used to.
D.The more things Americans like to have, the more water is neede
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