(  )45. A. where to laugh     B. who to laugh                   C. how to laugh

(A)

As we all know, the ocean moves. But waves(波浪) breaking on the beach make the ocean fun. When you stand on the shore (海岸) and look at the waves, it seems like the water is rolling (翻滚) in toward you. But the water is not really moving forward. What you see moving 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 moves the water that is under the basketball up and down as it passes.

   So why can you see a wave knock you down on the shore? When a wave moves toward the shore, the bottom(底部) of the wave slows down because it meets the ocean floor. But the top, which is called crest, 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.

根据短文内容选择最佳答案。

(  )44. A. many                  B. plenty of                        C. a lot

(  )43. A. while                  B. whenever                        C. whether

(  )42. A. in                       B. with                               C. under