As we all know, the ocean moves. But waves breaking on the beach make the ocean fun. When you stand on the shore and look at the waves, it seems like the water is moving towards you. But the water is not really moving forward. The moving you see is wave energy. And wave energy comes from the wind.

Let’s think about how this works. As wave energy passes through the water, the energy makes particles （粒子） of water move up and down. Just give you an example of a wave passing under a basketball. We put a basketball on the sea. When the wind blows, a wave comes from behind the basketball. The basketball moves up to the top with the wave. Then the wave continues and leaves the basketball behind. The basketball looks lower, but it doesn’t move forward. That’s because the wave energy just moves the water which is under the basketball.

　  So why can you see a wave knock you down on the shore？When a wave moves toward the shore, the bottom of the wave slows down because it meets the ocean floor. But the top, which is called crest(浪峰), keeps moving. The different action causes the wave to fall over or break onto the shore. If a wave is very large, it carries a lot of energy when it hits the land. As time goes by, waves can break up and carry away the rocks and other things on the shore. Shorelines are changing all the time because of wave action.

51. ______ is really moving forward when you look at the wave.

  A. Water      B. The basketball     C. Water and wave energy     D. Wave energy

52. Match the sentences with the pictures and the right answer.

   (1) The basketball moves up to the top with the wave.

   (2) The basketball continues and leaves the basketball behind.

   (3) When the wind blows, a wave comes from behind the basketball.

A. a—(2)  b—(1)  c—(3)              B. a—(3)  b—(1)  c—(2)

C. a—(1)  b—(3)  c—(2)              D. a—(3)  b—(2)  c—(1)

53. Which of the following is NOT true according to the passage?

  A. Wave energy comes from the water.

  B. Large waves carry plenty of energy.

  C. Wave action makes shorelines change all the time.

  D. The bottom of the wave is easy to slow down.

54. The underlined word “it” ( Paragraph 3) refers to “________”.

A. particles of water      B. the shore      C. the wind    D. the bottom of the wave

55. The main idea of this passage is ______.

  A. what makes particles of water move         B. how a basketball moves on the ocean

C. how wave energy causes wave action        D. why a wave can knock you down

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Supporting details

Future is now.

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Be7.    of today

Today’s hard work 8.   to tomorrow’s harvest. As students, we should never9.   what can be done today till tomorrow and we should try our 10.   to do everything well.

 

 

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