副词
1. The students are a month behind with the rent.
学生们已经拖欠了一个月的房租。
2. There is more behind.
里面还有文章。
介词
1. There must be something behind it.
其中必有隐情。
2. The senators are fully behind his welfare policy.
参议院的议员们完全支持他的社会福利政策。
3. George always falls behind his schedule.
乔治老是不能按时完成计划。