fall in
1．fall into sth．accidentally； drop into 掉入；跌入
The child was near the river and I was afraid he would fall in．孩子在河边，我怕他会掉进河里。
He plunged into the lake to rescue the child who'd fallen in．他跳进湖去救那个落水的孩子。
The water's deep here． Mind you don't fall in．这里水深，当心别跌进去。
2．sink inwards凹进
Because of long illness his eyes fell in．由于长期生病，他的眼睛向里凹陷。
3．agree同意
Once the chairman had stated his decision，the rest of the committee fell in．主席一宣布决定，委员会的其余成员都表示同意。
He made a very good suggestion at the meeting and we fell in immediately.他在会上提出了一个非常好的建议，我们立即同意了。
4．（of a debt）become payable；expire（债务）到期；满期
The city's debts fall in at the end of this year and the council are worried about paying them．市府的公债年底到期，市政会正为如何偿还这笔债务发愁呢。
The lease of the land has fallen in．土地的租期满了。
5．get into line；form ranks站队；集合
He ordered the men to fall in．他命令士兵集合。
At eight o'clock the students fell in．8点钟学生们集合。