Question

________ years ago, coal came from trees and other plants that grew on earth.

1. A.
   Million of
2. B.
   Million
3. C.
   Millions of
4. D.
   Millions

Answer 1

C
这里考查学习对million，thousand，hundred这类词的使用。
我们知道：“hundred”，“thousand”，“million”它们前面若有数词时，它们不能加s，即以单数形式出现；如果前面没有任何数词，则必须加S，且经常与of连用。例如：
Millions of people are holding a meeting on the square.
几百万人在广场上开会。
Five million sets of books are being printed.
500万套书正在付印。
Some millions of workers were on strike.
好几百万人罢了工。
Some two million fishes died in the river.
大约两百万条鱼死在河里了。