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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 certain physical things about it.A wave has height, from trough (low point) to crest (high Point).It has length-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 × frequency
Here, wavelength is the distance between two high points (crests), frequency means the number of cycles per second.
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1.What causes waves?
A.Earthquakes and nothing else. B.Only wind.
C.Wind causes most waves. D.Wind causes some waves.
2.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.
3.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.
查看习题详情和答案>>The law says women should have the chance of doing the same jobs as men and earn the same as them. The reality is very different. Women lose because, 25 years after the Equal Pay Act, many of them still get paid less than men. They lose because they do lower-paid jobs which men just won’t consider. And they lose because they are the ones who interrupt a career to have children. All t
his is reported in an independent study ordered by the Government’s women’s unit. The biggest problem isn’t equal pay in workplaces such as factories. It is the sort of work women do.
Make a list of low-paid-jobs, then consider who does them. Try nurses, secretaries, cleaners, clerks, teachers in primary schools, dinner ladies and child-care helpers. Not a lot of men among that group, are there? Yet some of those jobs are really important. Surely no one would deny that about nurses and teachers, for a start. So why do we reward the people who do them so poorly? There can be only one answer—because they are women. This is not going to be put right overnight. But the government, which emp
loys a lot of them, and other bosses have to make a start.
It is disgraceful(可耻的) that we have gone into the 21st century still treating women like second-class citizens.
【小题1】
Women should have the chance of doing the same jobs and getting the same pay as men_________.
| A.after 25 years |
| B.according to the law |
| C.as a result of those important jobs |
| D.because women are as strong as men |
.We can learn from the text that what really matters in this problem is_________.
| A.that women interrupt a career to have children |
| B.what sort of work women do |
| C.because they are women |
| D.what unfair pay women get in workplaces |
.Which of the following best describe the writer’s idea?
| A.Women and men should get equal pay for equal work. |
| B.Women should strengthen themselves. |
| C.The government ought to protect women against getting paid less than men. |
| D.Some of the jobs that women do are of great importance. |
Which do you think would be the best title for this passage?
| A.Work to give women a fair pay deal | B.The equal pay act |
| C.The sort of work women do | D.The biggest problem about women |
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