of the earth covered by water.A. Two thirds; is B. Two thirds; are C. One thirds; is

问题补充：

of the earth covered by water.

A. Two thirds; is B. Two thirds; are C. One thirds; is

答案：

解析：句意：地球的三分之二被水所覆盖。在英语中分子用基数词表达，分母用序数词表达如果分子大于1，分母变复数。分数，作主语时，根据其后接的词而定，如果为不可数名词，则相当于单数，如果其后接的为可数名词复数形式，则相当于复数。故选A