单选题 The water level of an ocean falls ______.

A、 when there is a low tide
B、 when the water is pulled away from the earth
C、 when the moon disappears over the horizon
D、 when water no longer moves

【正确答案】 C

【答案解析】本题测试对词汇的理解。答案来自As the moon disappears over the horizon，the pull lessens and the water level settles back towards the ocean bottom．问题中的falls意思是“settles back”。