Question

The water level of oceans rises and falls alternately(交替地)twice a day．This movement of water is called the tide．Tides are caused by the pull of the sun and the moon on the earth's surface; since the moon is much closer, it affects the tides more than the sun．When the moon is directly overhead, it actually pulls on the water that is below it．This causes the water level to rise because the water is pulled away from the earth．As the moon disappears over the horizon, the pull lessens(减少)and the water level settles back towards the ocean bottom． 　　When the water reaches its highest level, we have high tide．And when the water reaches its lowest level, we have low tide．From its lowest point, the water rises gradually for about six hours until it reaches high tide．Then it begins to fall continuously for about six hours until it reaches low tide．Then the cycle begins again． (1) The water level of oceans rises and falls ________． [　　] A． twice a day． B． every other day C． twice a week． D． only during the summer (2) The article says that the rise and fall of the ocean's water level ________． [　　] A． affect the moon． B． disturb the ocean bottom． C． change the earth's surface． D． are called the tides． (3) The article says that tides are caused by the ________． [　　] A． heat of the sun． B． pull of the sun and the moon． C． shape of the moon． D． light of the moon． (4) When the moon is directly overhead, it ________． [　　] A． calms the water below it． B． pulls the water below it． C． pushes the water below it． D． does not affect the water below it． (5) We have a high tide when the ________． [　　] A． water level is at its lowest point． B． water starts to rise． C． water level is at its highest point． D． moon disappears over the horizon．

Answer 1

答案：1．A;2．D;3．B;4．B;5．C;