in
介词 prep.
1.在...里,在...上
The two brothers study in the same class.
两兄弟在同一个班里上课.
The telephone is in the little study on the ground floor.
电话在一楼的小书房内.
2.在...之内;在...方面
He is lacking in courage.
他缺乏勇气.
3.从事于;参加着
She is in business.
她做生意.
4.穿着,戴着
He is dressed in black.
他穿黑衣服.
5.朝,向
She hurried away in the opposite direction.
她朝相反的方向匆匆离去.
6.(表示手段、方法、材料)用,以
They paid in cash.
他们用现金支付.
7.在...期间;在...以后
He'll come back in a week.
他将于一周之后回来.
I haven't met her in a long time.
我好长时间没有遇见她了.
8.处在...中
The room was in disorder.
房间里乱七八糟.
9.(表示数量、程度、比例)按,以;在...中
One child in twenty has this disease.
二十个小孩中有一个患有这种疾病.
10.在...身上,在...上
In him I see a future leader.
我在他身上看到了一个未来的领袖人物.
11.(表示过程)在...当儿;在...
The work is in progress.
这工作正在进行中.
12.(表示动作的方向和结果)进入到...中;成,为
He pushed a button and set the machine in motion.
他按下按钮开动了机器.on
介词 prep.
1.在...上
He laid a hand on my shoulder.
他把一只手放在我肩上.
2.以...支持,挂在...上;以...为轴
There is a picture on the wall.
墙上有一幅画.
3.朝,向
4.靠近,在...旁,沿着
She stood on my left.
她站在我左边.
5.在...的时候,在...后立即
He jumped with joy on hearing the news.
他一听到这个消息就高兴得跳了起来.
6.关于,有关
The teacher made comments on our compositions.
老师就我们的作文作了讲评.
7.以...方式,通过
Did you hear it on the radio?
你是从收音机听到这消息的吗?
8.凭...,靠...;使用...,吃...
They said they were acting on instructions.
他们说他们是奉命行事.
9.处于...状态,进行中
10.属于...,参加...,是...的成员
He is on the school volleyball team.
他是校排球队队员.
11.加之于,重叠于
12.由...支付
Have another coffee on me.
再来一杯咖啡,我请客.
13.带在...身上at
介词 prep.
1.在...地点
They were already waiting at the gate when I got there.
当我到达那里时,他们已等候在门口了.
2.在...时刻
Jane will meet her boy friend at Christmas.
简将在圣诞节和她男友见面.
3.向,朝,对着
Don't shout at me.
别对我叫喊.
4.在...方面
He is an expert at troubleshooting.
他是位排解争端的能手.
5.因为,由于
I woke at the sound of the bell.
随着铃响,我醒了.
6.从事于,忙于
He is working hard at this thesis.
他正在努力地撰写论文.
7.以(某种价格、速度等)
They sold the cloth at a dollar a yard.
他们以每码一
简单地说,这三个介词主要体现在习惯表达方面：如:in the field,in the air,in the morning(泛指）,on the farm,on the morning of last Sunday（特指） ,at noon,等
补充：in在范围内,on两地接壤,
