问题补充:
(·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
答案:
(答案→)A. why
B. how
C. because
D. whether
解析: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。