会有某些人说，“我告诉过你了！”

There will be certain people who'll say "I told you so!"

《柯林斯英汉双解大词典》

我已经告诉过你了，你不要说话。

I've told you before, you must not talk.

youdao

我已经告诉过你了，你没在听吗？

I have told you, weren't you listening?

youdao

I can tell you the answer, but that's because I've cheated, run the program before.

我可以告诉你答案，但这是因为我作弊了，我之前运行过一次程序。

麻省理工公开课 - 计算机科学及编程导论课程节选

You could tell your friend that you've tried it and it didn't work by using the "I've already" pattern.

你可以用“I've already”句型告诉你朋友，你已经用过了，却没什么效果。

I've already 课堂 - SpeakingMax英语口语达人

You could tell him that you've already taken care of it by using the "I've already" pattern.

你可以用“I've already”句型告诉他你已经处理过那个问题了。

I've already 课堂 - SpeakingMax英语口语达人