Question

又是语法 couldn't 和won't 区别

Answer 1

couldn't 是很委婉的can't,比较公式化。 例如。。。I couldn't kill him.

而won't 则是很铁定，很坚决的拒绝，跟can't有比较大的区别。 例如。。。 I won't kill him.

希望能帮到你。