could not 和couldn't的区别为

could not 释义：

不能

例句：

She could not move unassisted.

她不能够独力活动。

My euphoric mood could not last.

我兴奋的心情持久不了。

couldn't释义：

v. 不能（等于could not）

例句：

I couldn't trust him anymore.

我再不能相信他了。

词组：

couldn't help禁不住；不得不。