Question

【题目】The boy was so weak that he________ move by himself.

A. was able to B. was unable to

C. is not able to D. was disabled to

Answer 1

【答案】B

【解析】

句意：那个男孩如此虚弱以至于他自己不能移动。be able to 能；be unable to 不能。根据主句时态是过去时态，所以从句用过去时态，结合句意，故选B。