- (屋顶、墙壁等)凹进去，塌陷，往里面塌陷；(眼睛、脸颊)凹陷，消瘦：
The roof of the burning house fell in.
着火屋子的房顶塌陷了下去。
Her cheeks had fallen in,making her look old.
她的脸颊凹陷下去了，使她看上去很苍老。
- 【军事】(使)入列，(使)集合，排好队列：
Fall in!
集合!
The troops fell in and were inspected.
部队集合好，接受检阅。
- 掉进去，跌入：
The water's deep here,mind you don't fall in.
这里水很深，你请注意不要掉下去。
- (租约等)期满(或失效)，(债务等)到期：
When will the lease fall in?
租约将于何时到期?
- (土地、产业等)可以支配使用：
At his lordship's death in the Spanish campaign in the year 1811,his estate fell in to the family of the Tiptoffs.
这位爵爷在1811年西班牙战役中死亡后，他的产业归蒂普托夫家族支配。
- 同意，赞成：
Once the chairman had stated his decision,the rest of the committee fell in.
主席一说出他的决定，其他委员就表示了同意。
I fell in with his view.
我赞同他的观点。
- 在(某人心目中)降低：
The chairman fell in my opinion after he refused to take a vote.
主席拒绝进行投票表决后，他的地位在我的心目中就降低了。
- 和解，言归于好：
They fall in and out ten times a day.
他们一会儿和好，一会儿闹翻，一天有上十次。