Wind is the great maker of waves. There are exceptions, such as the tidal (潮汐的) waves sometimes produced by earthquakes under the sea. But the waves most of us know are produced by winds blowing over the sea .Now before constructing an imaginary life history of a typical wave, we need to know certainphysical things about it. A wave has height, from trough ( low point) to crest ( high Point) . It has lengh-the distance from this crest to that of the following wave. The period of the wave means the time it takes for succeeding crests to pass a fixed point. None of these things stays the same--for all depend upon the wind, upon the depth of the water and many other matters.The water that makes up a wave does not advance with it across the sea. Each drop of water turns around in a little circle with the passing of the wave, but returns very nearly to its original position. And it is fortunate that this is so. For if the huge masses of water that make up a wave actually moved across the sea, sailing would be impossible.If we want to find the speed of a wave, we may use the following way :Speed = wavelength × frequencyHere, wavelength is the distance between two high points (crests) , frequency means the number of cycles per second 18. What causes waves?A. Earthquakes and nothing else. B. Only wind.C. Wind causes most waves. D. Wind causes some waves.19. Which of the following is true according to the passage?A. The water of a wave moves away across the sea.B. The water of a wave remains almost at the same place.C. The water of a wave goes with the passing of the wave.D. The length of a wave means the distance from the top of a wave to the bottom.20.The speed of Wave 1 is 100 cm/s, frequency 10. The frequency of Wave 2 is 300, while its speed is twice that of Wave 1. Which of the following is right?A . The wavelengths of the two are equal.B. The wavelength of Wave 1 is 10 times longer than that of Wave 2.C. The wavelength of Wave 2 is longer than that of Wave 1.D. The wavelength of Wave 1 is longer than that of Wave 2.答案DACBD翻译风能是波浪大制造商.但也有例外,如潮水（潮汐的）,有时是根据地震产生的海浪.不过,波大多数的人都被吹的海面风造成的.
现在才兴建一个典型的波想象生命的历史,我们需要知道一些
对此物理事物. A波从低点（高点）波峰（高点的高度）.它有国境线,从这个波峰距离下面的浪潮.在波期间的意思是,它成功的徽章需要通过一个固定点.这些东西没有保持不变-所有取决于风后水的深度和许多其他事项.
水是构成了波浪不事先与它隔海相望.每一滴水转身在与波通过小圆圈,但回报率非常接近到原来的位置.它是幸运的,这是如此.因为如果水的庞大群众,使一个浪潮,实际上在海上移动,航行是不可能的.
如果我们想找到一个波的速度,我们可以采用下列方式：
速度=波长×频率
在这里,波长是两个（波峰）高点的距离,频率指每周期数第二
18.波是什么原因?
答：地震,别无其他. b.只有风.
C.风导致大部分波. D.风导致一些波浪.
19.下列哪项是正确根据的通过?
答：波浪的水迁离隔海相望.
B的波水仍然几乎在同一个地方.
长波浪的水去同波传递.
D.对波浪的长度是指从波浪的顶部距离底部.
20.The波1速度100厘米/秒,频率10.在第2波的频率是300,而其速度的两倍波1.下列哪项是正确的?
阿.两者的波长是相等的.
B的波1波长的10倍以上的波2的.
丙级第2波的波长长于波1的.
D.对波1波长长于波2的. Wind is the great maker of waves. There are exceptions, such as the tidal (潮汐的) waves sometimes produced by earthquakes under the sea. But the waves most of us know are produced by winds blowing over the sea .Now before constructing an imaginary life history of a typical wave, we need to know certainphysical things about it. A wave has height, from trough ( low point) to crest ( high Point) . It has lengh-the distance from this crest to that of the following wave. The period of the wave means the time it takes for succeeding crests to pass a fixed point. None of these things stays the same--for all depend upon the wind, upon the depth of the water and many other matters.The water that makes up a wave does not advance with it across the sea. Each drop of water turns around in a little circle with the passing of the wave, but returns very nearly to its original position. And it is fortunate that this is so. For if the huge masses of water that make up a wave actually moved across the sea, sailing would be impossible.If we want to find the speed of a wave, we may use the following way :Speed = wavelength × frequencyHere, wavelength is the distance between two high points (crests) , frequency means the number of cycles per second 18. What causes waves?A. Earthquakes and nothing else. B. Only wind.C. Wind causes most waves. D. Wind causes some waves.19. Which of the following is true according to the passage?A. The water of a wave moves away across the sea.B. The water of a wave remains almost at the same place.C. The water of a wave goes with the passing of the wave.D. The length of a wave means the distance from the top of a wave to the bottom.20.The speed of Wave 1 is 100 cm/s, frequency 10. The frequency of Wave 2 is 300, while its speed is twice that of Wave 1. Which of the following is right?A . The wavelengths of the two are equal.B. The wavelength of Wave 1 is 10 times longer than that of Wave 2.C. The wavelength of Wave 2 is longer than that of Wave 1.D. The wavelength of Wave 1 is longer than that of Wave 2.答案DACBD翻译风能是波浪大制造商.但也有例外,如潮水（潮汐的）,有时是根据地震产生的海浪.不过,波大多数的人都被吹的海面风造成的.
现在才兴建一个典型的波想象生命的历史,我们需要知道一些
对此物理事物. A波从低点（高点）波峰（高点的高度）.它有国境线,从这个波峰距离下面的浪潮.在波期间的意思是,它成功的徽章需要通过一个固定点.这些东西没有保持不变-所有取决于风后水的深度和许多其他事项.
水是构成了波浪不事先与它隔海相望.每一滴水转身在与波通过小圆圈,但回报率非常接近到原来的位置.它是幸运的,这是如此.因为如果水的庞大群众,使一个浪潮,实际上在海上移动,航行是不可能的.
如果我们想找到一个波的速度,我们可以采用下列方式：
速度=波长×频率
在这里,波长是两个（波峰）高点的距离,频率指每周期数第二
18.波是什么原因?
答：地震,别无其他. b.只有风.
C.风导致大部分波. D.风导致一些波浪.
19.下列哪项是正确根据的通过?
答：波浪的水迁离隔海相望.
B的波水仍然几乎在同一个地方.
长波浪的水去同波传递.
D.对波浪的长度是指从波浪的顶部距离底部.
20.The波1速度100厘米/秒,频率10.在第2波的频率是300,而其速度的两倍波1.下列哪项是正确的?
阿.两者的波长是相等的.
B的波1波长的10倍以上的波2的.
丙级第2波的波长长于波1的.
D.对波1波长长于波2的.