but if you explain it to your friend that you or she should not have or should have done something,

如果你想要向你的朋友解释，或者她应该做某事的时候，

I should have 课堂 - SpeakingMax英语口语达人

Use this pattern in any situation where you want to explain you've done it before.

当你想解释之前已经做过某事的时候，可以在各种情形下使用这个句型。

I've already 课堂 - SpeakingMax英语口语达人

You want to use the "so ~ that" pattern to help you explain why you can or can't do something.

使用 “so ~ that”句型可以帮助你解释你能够或者不能够做某事的原因。

so that 课堂 - SpeakingMax英语口语达人