Question

Some scientists think that it will take __ of years to make robots do most work for humans

1. A.
   hundreds
2. B.
   hundred
3. C.
   thousand

Answer 1

A
考查数词的用法。固定短语hundreds of“成百上千”、thousands of“成千上万”；如果前面没有具体的数字，常用复数加of结构表示不确切的数字。