书包在门后面用英文怎么说

"书包在门后面"用英语可以说成 "the backpack is behind the door"。

"behind"是英语中的副词，表示"在...后面"的意思。

例句:

My keys are behind the door. 我的钥匙在门后面。
The dog is hiding behind the couch. 狗躲在沙发后面。
The sun is setting behind the mountains. 太阳在山后面落下。