oughtn't, mustn't, can't区别

问题描述:

oughtn't, mustn't, can't区别

从意义上来解释 oughtn't 是不需要的意思 mustn't是不可能的意思 can't是不能够的意思
从语气上来讲 mustn't 的语气最否定 can't次之 oughtn't最为委婉