didn't 和couldn't的区别,

didn't 和couldn't的区别, why not,why didn't,why couldn't的区别 couldn't have done和couldn't do的区别 I couldn't get to school on time和I didn't get to school on time有什么区别?couldn't 和 didn‘t 能不能互用? couldn't和shouldn't的区别,急要 can't和couldn't区别? couldn't与can't的区别! can't与couldn't的区别 I couldn't bear it 和I couldn't bear this的区别 could和 must和 couldn't 的区别和用法? can’t 和 won’t didn’t doesn’t 的区别是啥can’t 和 won’t didn’t doesn’t 的区别是啥 hadn't 和 didn't have的区别RT couldn't don't have to needn't的区别 i don t know和I didn't know的区别什么时候用don't,什么时候用didn't couldn't have finished和 can't have finished 的区别 couldn t和 didn't think 和never thought 的区别是什么? aren't/didn't/isn't you?他们的区别