Don't go behind my back.

不要跟在我后面。

youdao

I can't believe you would go behind my back.

我不敢相信你竟背着我干这样的事。

youdao

Did you go to see your old flame behind my back yesterday?

你昨晚背着我去跟你的旧情人约会了吗？

youdao

I must go back, I've left my car keys behind.

我必须回去，我忘了带汽车钥匙。

youdao

I must go back; I've left my car keys behind.

我必须回去，我忘带汽车钥匙了。

youdao

I must go back; I've left my car keys behind.

我必须回去，我忘带汽车钥匙了。

youdao