Question

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

Answer 1

C

why為什么;how怎樣, 如何;because因為;whether是否. 句意:從太空中望去, 地球看起來是藍色的. 這是因為它的表面大約百分之七十被水覆蓋. why在引導(dǎo)表語從句時強調(diào)結(jié)果，如: She was ill. That’s why she was sent to the hospital. 她病了，所以被送到醫(yī)院來(那就是她為什么被送到醫(yī)院的原因)。Because引導(dǎo)表語從句強調(diào)原因,結(jié)合語境可知選C.
【考點定位】連詞辨析