英语中常见的敲门句子包括：

Knock at the door。

Knock on the door。

Hey, can you hear me？ I'm knocking at the door.。

I'll just knock on the door and see if anyone's home.。

Please knock on the door before entering.。

I heard someone knocking at the door.。

Did you hear a knock at the door？。

I heard a knocking sound but it wasn't （at） the door.。

这些句子在不同的语境下都可以用来表达敲门的行为，可以根据具体情况选择合适的表达方式。