suffer:

1.做不及物动词，不加宾语，译为受苦。

She suffered greatly as a child.她童年深受苦难。

2.做及物动词，译为忍受。 He could not suffer criticism. 他不能忍受别人批评他。

suffer from：

1.患(某种病); 受(某种病痛)折磨You must have suffered from a cold. 你一定是感冒了。

2.因…而受罚〔苦, 损〕Sometimes I still suffer from these weaknesses.有时我还是在吃这些弱点的苦头。