1.在（某范围或空间内的）某一点 at a point within an area or a space
例：a country in Africa
非洲的一个国家
2.在（某物的形体或范围）中；在…内；在…中 within the shape of sth; surrounded by sth
例：She was lying in bed.
她躺在床上。
3.进入
into sth
例：He dipped his brush in the paint.
他把毛刷在涂料里蘸了蘸。
4.构成…的整体（或部分）；包含在…之内 forming the whole or part of sth/sb; contained within sth/sb
例：There are 31 days in May.
五月份有31天。
5.在（某段时间）内 during a period of time
例：in 2005
在2005年
6.在（某段时间）之后
after a particular length of time
例：to return in a few minutes/hours/days/months.
几分钟 / 几小时 / 几天 / 几个月后回来
7.(used in negative sentences or after first , last , etc. 用于否定句或first、last等之后) 在（某段时间）内 for a particular period of time
例：I haven't seen him in years.
我有好些年没见过他了。
8.穿着；戴着
wearing sth
例：dressed in their best clothes
穿着他们最好的衣服
9.（用以描述具体的环境） used to describe physical surroundings
例：We went out in the rain.
我们冒雨出去了。
10.（表示状态或状况） used to show a state or condition
例：I'm in love!
我恋爱了！
11.参与；参加 involved in sth; taking part in sth
例：to act in a play
12.参加演戏（显示工作或职业）
used to show sb's job or profession
例：He is in the army.
他在军队服役。
13.（显示某物的形式、形状、安排或数量） used to show the form, shape, arrangement or quantity of sth
例：a novel in three parts
分为三部的小说
14.（表示使用的语言、材料等） used to show the language, material, etc. used
例：Say it in English.
用英语说吧。
15.关于；在…方面 concerning sth
例：She was not lacking in courage.
她并不缺乏勇气。
16.做…时；…发生时；当…时 while doing sth; while sth is happening
例：In attempting to save the child from drowning, she nearly lost her own life.
她在抢救落水儿童时，自己差点丧命。
17.（引出具某种品质的人的名字） used to introduce the name of a person who has a particular quality
例：We're losing a first-rate editor in Jen.
我们即将失去珍这位一流的编辑。
18.（显示比率或相对数量） used to show a rate or relative amount
例：a gradient of one in five
五分之一的坡度