如果你要来派对，请告诉我。

___Let me ___know if you're coming to the party.

我只是想让你知道我们要用蓝色油漆，因为我真的很喜欢蓝色。

I just want to ___let you ___know that we are going to use blue paint because I really like blue.

请在你到达时告诉我们。

Please ___let us ___know when you arrive.