He is never behind with [in] his work.
他工作从不拖拉。
He was behind in [with] his rent.
他拖欠了房租。
He helped a classmate who was behind with his homework.
他帮助一位没有按时完成作业的同班同学。
2 . be behind in doing sth 做某事不落在后面。如：
The boy is behind in handing in homework.
这孩子没能按时交家庭作业。
He was never behind in offering suggestions.
他提建议从来不落在别人后面。
3 . from behind 从后面。如：
He held her from behind.
他从后面抱住她。
They attacked us from behind.
他们从后面攻击我们。
注：有时 behind 是介词，其后可接宾语。如：
He came out from behind the door.
他从门后出来。
4 . fall [drop ] behind 落在后面。如：
I’ve fallen behind in work. 我工作落后了。
Some students dropped behind in their studies.
有的学生在学习上落在后面。
5 . leave sth behind 走后留下某物。如：
What have we left behind?
我们走后留下什么了?
He left his umbrella behind.
他离开时没有把雨伞带走。
6 . stay [remain ] behind 留下，在别人后面留下。如：
He alone remained behind.
只有他一个人留下没走。
I had to stay behind after school.
放学后我还得留在学校。
