off 可用作介词或副词，基本义为“离开”“脱落”“中止”等。如：
I’m afraid I must be off now. 恐怕现在我得走了。
Take off your hat in the house. 在室内请脱帽。
We are off for [to] Paris. 我们要动身去巴黎。
He fell off the ladder. 他从梯子上摔下来。
Is the radio on or off? 收音机是开着的还是关着的?
2：用来指时间或距离有多远，与 away 同义，有时可换用。如：
The exam is only two weeks off [away]. 考试只两周了。
The school is about two miles off [away]. 学校离这里大约两英里。
3：表示休假或不工作，若用作副词，放在名词之后；若用作介词，放在名词之前。如：
I’ll have four days off. 我要休4天假。
I’ll take the afternoon off. 我今天下午休息。
Mr Smith is off duty today. 史密斯先生今天不上班。
He practised playing the piano in his off hours. 他在业余时间练习弹钢琴。
from介词prep.
1.从...起,始于 eg:She is singing from morning to night.她从早唱到晚.
2.从;由
eg:He rose from office boy to managing director in fifteen years.
他十五年里从办公室勤杂员升到总经理.
3.离(开) eg:Our school is two miles from the station.我们学校离车站两英里.
4.从...来;出自 eg:He comes from Shanghai.他来自上海.
5.(表示去除、免掉、阻止、剥夺等) eg:The pill will relieve you from pain.这药丸将使你免受痛苦.
6.(表示区别、比较) eg:He is old enough to know right from wrong.他已长大,能够辨别是非了.
7.(表示原料)由 eg:Flour is made from wheat.面粉由小麦制成.
8.因为,由于;出于
eg:He wasn't ill; he stayed in bed from laziness.他没病,躺在床上是因懒惰之故.
eg:He is trembling from fear.他吓得发抖.
8.across from⋯.在...的对面
eg.The post office is just across from the club .邮局就在那俱乐部对面.
for1.表示“当作、作为”.如:
I like some bread and milk for breakfast.我喜欢把面包和牛奶作为早餐.
What will we have for supper?我们晚餐吃什么?
2.表示理由或原因,意为“因为、由于”.如:
Thank you for helping me with my English.谢谢你帮我学习英语.
Thank you for your last letter.谢谢你上次的来信.
Thank you for teaching us so well.感谢你如此尽心地教我们.
3.表示动作的对象或接受者,意为“给……”、“对…… (而言)”.如:
Let me pick it up for you.让我为你捡起来.
Watching TV too much is bad for your health.看电视太多有害于你的健康.
4.表示时间、距离,意为“计、达”.如:
I usually do the running for an hour in the morning.我早晨通常跑步一小时.
We will stay there for two days.我们将在那里逗留两天.
5.表示去向、目的,意为“向、往、取、买”等.如:
Let’s go for a walk.我们出去散步吧.
I came here for my schoolbag.我来这儿取书包.
I paid twenty yuan for the dictionary.我花了20元买这本词典.
6.表示所属关系或用途,意为“为、适于……的”.如:
It’s time for school.到上学的时间了.
Here is a letter for you.这儿有你的一封信.
7.表示“支持、赞成”.如:
Are you for this plan or against it?你是支持还是反对这个计划?
8.用于一些固定搭配中.如:
Who are you waiting for?你在等谁?
For example,Mr Green is a kind teacher.比如,格林先生是一位心地善良的老师.