1． Question：
pay the postage for the parcel 中的for
和 pay the postage on Alice's letter 中的on
有什么区别呢？？
为什么要分别用两个介词呢
需要比较详细的解释，谢谢
Answere：
pay the postage for the parcel 中的for为邮寄包裹付费用
pay the postage on Alice's letter 中的on指在Alice的信封上付费用即邮寄信件付邮递费<如邮票>
(1)介词for----“关于，对于……来说，考虑到……的事实”
e.g. The weather is quite warm for November. 对十一月来说，这儿的天气很暖和了。
e.g. For him, this will be an entirely new hobby. 对他来说，这是全新的爱好。
引导原因状语从句的连词
原因状语从句一般由because, since, as, for引导
for表示所说的理由是一种补充说明,因此,for引导的从句可以放在括号里,而且for引导的从句一般不放在句子的开头。例如:
  I decided to stop and have lunch, for I was feeling quite hungry.
介词on和动名词搭配,表示一个动作。”一...就...” on seeing him,I ran away.
2. Question： 1.for 与because用法有何区别
2.although与 though用法有何区别?
3.which与that用法有何区别?
Answeres：
for 与because用法有何区别
for是用来表示推断的原因或者对主句进行说明的；because引出直接的原因。
如：
1.He must be at home，for the light in his home is still burning.
2.It must have rained last night，for the road is still wet.
3. He didn‘t attend the meeting yesterday because he was ill.
although与 though用法有何区别?
在现代英语中作“虽然.....但是”讲时，它们的区别不明显。但though可以用作于倒装句。
如：
1. Mother though she is，she doesn’t like children.
2. Hard though he worked， he didn‘t pass his final exam.
which与that用法有何区别?
A。在名词性从句中，which“哪一个/哪一些”的意思；that而是不作成分的。
1. Which is the longest river in the world？
2. He told me that he did not like this film。
3. Did he tell you which film he liked most？
B。在定语从句中：
关系代词that的使用场合
1．在以疑问词who开始的句子中，避免两个who重复，用that。如
Who is the man that is shouting there？
2．关系代词在从句中作表语时，多用 that。如：
She is not the girl that she was three years ago．
3．先行词被形容词最高级、only等修饰时，应用that。如：
Tang Guoqiang has become one of the best actors that appear on Chinese screens．
4．先行词人和物两者都有时，要用that。如：
He talked about the teachers and schools that he had visited．
5．关系代词与the same（指同一人）连用时，只能用that。如：
This is the same person that I met yesterday．
6．一个句子中有两个定语从句时，如第一个从句中已用who，第二个从句中宜用that。如：
The man who is at table is his brother that has been serving in the army．
二、关系代词that和which的选择
关系代词that和which都可以指物，在很多场合两者都通用。但有时that和which的使用场合并不相同。
（一）关系代词which的使用场合
1．如果先行词是that，关系代词应用 which。如：
What was that which you said about him ？
2．先行词和定语从句之间被其它较长的成分分隔，用which较好。如：
I have some interests outside my professional work which gives me great pleasure．
3．一个句子中如有两个定语从句，第一个定语从句用了关系代词that，第二个从句宜用which。如：
This is the book that you bought which you have lost．
但在平行结构中，应重复同一个关系代词。如：
I have a house which is located on the hillside，which faces the south．
4．非限制性定语从句中关系代词一般要用which。如：
I will buy a book，which tells about the use of English idioms．
5．相当于并列句和状语从句的定语从句，用which引导。如：
1）We went to the nearest port which we reached safely．
2）He persisted in having a bicycle which he actually had no use for．
6．关系代词前如有介词，关系代词要用 which。如：
They had a meeting at which he spoke on the current econom ic situation．
如把介词移至句末，可用that（或省略）。如：
This is the book（that）she was looking for．
（二）关系代词that的使用场合
1．一般说来，先行词是all，anything，everything，nothing，much，little，few等，关系代词应用that。如：
1）That's all（that）I know．
2）Everything that can be done is done．
2．先行词之前有all，any，every，no，lit- tle，m uch，only，very等修饰时，关系代词应用that。如：
1）He'll read all the books that are sold here．
2）Ask any questions（that）you don't understand．
3．先行词前有序数词或形容词最高级修饰时，关系代词应用that。如：
1）This is the most wonderful film that I have ever seen．
2）The first thing that you should do is to work out a plan．
4．当先行词是to be的表语，或关系代词本身是从句的表语时，关系代词应用that。如：
1）It's a song that is very popular．
2）My hometown is no longer the place that it used to be．
5．当主句以There be开头时，关系代词应用that。如：
There is a seat in the corner that is still free．
6．当一个句子中含有两个定语从句时，如前一个已用关系代词which，后一个关系代词宜用that。如：
sort of look atme什么意思I'll borrow a book which tells about the heroic deeds that the PLA did in the battles against the invaders．
但两个定语从句的结构如果平行，一个定语从句中用关系代词that，另一个定语从句也应重复that。如：
He told me to read a book that is very short，and that is vey interesting．
7．与the same（指同一物）连用，构成the same．．．that．．．结构时，关系代词只能用that。如：
This is the same museum that you once visited．
注意：thes ame．．．that．．．结构中的that不能用as代替，因为the same．．．as．．．与the same．．．that．．．的含义不同。
3. Question：
英语中总是搞不清楚for ,of 的用法，有哪位高手请帮忙解答
Answeres：
for ,of 的用法很多，基本的是：
for：“为，给”的意思。如：It’s for you。
《表示目的，愿望》为，求”。如：What do you want the money for？
《表示时间，距离》。。。之久。如:for a while 。