for

1. We have studied English for years.
   我们学英语已有好几年了。
2. They jumped for joy.
   他们高兴地跳了起来。
3. Jim is going to get material for a new book.
   吉姆正打算为一部新书准备材料。
4. It is for her own good.
   这是为了对她自己有好处。
5. He has a great respect for his father.
   他很敬佩他的父亲。
6. What can I do for you?
   要我帮忙吗？
7. Are you for or against?
   你是赞成还是反对？
8. He shook his head, for he thought differently.
   他摇摇头，因为他的想法与此不同。

for

prep.（介词）

Used to indicate the object, aim, or purpose of an action or activity:
为了：用来指一个动作或活动的目的、目标或意图：
例句：
trained for the ministry; put the house up for sale; plans to run for senator.
为政府部门培训；把房子拍卖；计划竞选议员

Used to indicate a destination:
往，向：用来指目的地：
例句：
headed off for town.
出发去城里

Used to indicate the object of a desire, an intention, or a perception:
对于：用来指愿望、意图或感觉的目标：
例句：
had a nose for news; eager for fame and fortune.
消息灵通；渴求名利

Used to indicate the recipient or beneficiary of an action:
为：用来指一个活动的接受者或受益者：
例句：
prepared lunch for us.
为我们准备午餐

On behalf of:
代表：
例句：
spoke for all the members.
代表全体成员发言

In favor of:
对…支持：
例句：
Were they for or against the proposalô
他们支持这项议案还是反对呢ô

In place of:
代替…：
例句：
a substitute for eggs.
鸡蛋的替代品

Used to indicate equivalence or equality:
等值，等量：用于表示等值或相同关系：
例句：
paid ten dollars for a ticket; repeated the conversation word for word.
花十美元买了张票；逐字逐句地重复谈话

Used to indicate correlation or correspondence:
用于表示关联或联系：
例句：
took two steps back for every step forward.
每前进一步向后退两步

Used to indicate amount, extent, or duration:
达：用于表示数量、范围或持续时间：
例句：
a bill for five dollars; walked for miles; stood in line for several minutes.
五美元的钞票；步行了数英里；排了几分钟的队

Used to indicate a specific time:
在：用于表示一个具体时间：
例句：
had an appointment for two o`clock.
两点钟有一个约会

As being:
当作：
例句：
take for granted; mistook me for the librarian.
视为当然；把我误认为是图书管理员

Used to indicate an actual or implied listing or choosing:
针对…：用于表示实际的或隐含的列举或选择：
例句：
For one thing, we can`t afford it.
第一，我们买不起

As a result of; because of:
由于；因为：
例句：
jumped for joy.
因高兴而跳起来

Used to indicate appropriateness or suitability:
用于表示适度或适当：
例句：
It will be for the judge to decide.
这要由法官来决定

Notwithstanding; despite:
虽然；尽管：
例句：
For all the problems, it was a valuable experience.
尽管还存在许多问题，这仍不失为一次宝贵的经验

As regards; concerning:
关于；至于：
例句：
a stickler for neatness.
有洁癖的人

Considering the nature or usual character of:
至于：关于…的性质或一般特征：
例句：
was spry for his advanced age.
就他的高龄来说，他应该算是充满生气的了

In honor of:
为纪念…：
例句：
named for her grandmother.
为纪念她的祖母起的名字

conj.（连接词）
Because; since.
因为；既然

来源：
Middle English
中古英语
from Old English * see per
源自 古英语 *参见 per