be able to和able to区别

问题描述

精选答案

be able to 能够

a. 位于助动词后。

b. 情态动词后。

c. 表示过去某时刻动作时。

d. 用于句首表示条件。

e. 表示成功地做了某事时，只能用was/were able to， 不能用could。

He was able to flee Europe before the war broke out. =

He managed to flee Europe before the war broke out.