下面有几道英语的选择题，不太懂、清楚，要解释下

Question

1. i have many friends，…of whom…… some　are businessmen
这道题为什么要加介词of,

2. the place........the bridge is supposed to be built should be....... the cross-river traffic is the heaviest.
A which;where B at which ;which C at which; where D.which; in which
1.； 是非限制性定语从句，i have many friends 后面有一个逗号的
2，是选择C，具体的不清楚

给出详细的解释

Answer 1

1.句子原来形式为：i have many friends， some of whom are businessmen，题意是变形了下而已，这回明白？
2.C。
The place at which the bridge is supposed to be built should be where the cross-river traffic is the heaviest.
由简入繁演化一下：
The place should be where the cross-river traffic is the heaviest.
The place at which the bridge is supposed to be built should be where the cross-river traffic is the heaviest.
at the place 也可以理解为 在。。地方。追问

1.这道题为什么可以把some 和 of whom 倒过来？
2，这道题是定语从句和状语从句，应该怎么看？不太清楚

Answer 2

1，从句是some of them are businessman,them=who,做主语，但是，有了介词of,不能用of who,所以用of whom
2第一个是定语从句，从句是be supposed at结构,缺宾语，所以是at which,第二个是状语从句，地点状语从句，用where追问

2 。 后面的那个怎么看，后面的成分，，，，to be built should be ,,,又怎么解释呢

追答

the bridge should be built in the place ( where) the cross-river traffic is the heaviest
如果有the place,那就是定语从句
但是没有先行词，( where) the cross-river traffic is the heaviest就是地点状语从句

本回答被提问者采纳

Answer 3

1,表示你的这些朋友中，有做什么的，还有做什么的，表示类别。。。。of whom表示介滨短语
2，宾语从句。。。

Answer 4

第一题.因为在这里of意为在他们之中
第二题.D