Question

(2013·安徽，21)From space, the earth looks blue.This is ________about seventy­one percent of its surface is covered by water.

A．why

B．how

C．because

D．whether

Answer 1

A

考查名词性从句。此处考查表语从句。根据句意：地球看起来是蓝色的。这是因为其表面71%是被水覆盖的。