From space, the earth looks blue. This is _______ about seventy-one percent of its surface is covered by water.
A.why |
B.how |
C.because |
D.whether |
推荐套卷
From space, the earth looks blue. This is _______ about seventy-one percent of its surface is covered by water.
A.why |
B.how |
C.because |
D.whether |