介词加关系代词的复杂用法,就是many of which 怎么用

the instruments by means of which the temperature is measured is called.
the instruments is called是句子的主干
by means of which the temperature is measured =which the temperature is measure by means of (是定语从句部分,which指the instruments,which作了by means of 的宾语）
they asked a lot of questions ,many of which i don't know...
many of which i don't know是非限制性定语从句,know的宾语是many of which ,which指questions)
又如：I have two sisters,both of whom are dancers
both of whom are dancers是非限制性定语从句,WHOM 指sisters
There was no room in which they could live.
in which ( in which = where)they could live.是定语从句,=which they could live in
which 指room
关键是你要弄明白which指什么!

分成两个句子 They asked a lot of questions. Many of them I don't know.
改成定语从句，只要把句号改成逗号， them 改成which或whom
eg. I have many books. Some of them are interesting.
变成 I have many books, some o...