请教几个高中定语从句的问题！

Question

顺便解释一下为什么！谢谢！
1、I will call on my friend Tom, the manager( )company is my father's student.
A.of whom B.of whose C.whose D.which
2、 It is our parents ( )we depend when we are in trouble.
A.whoever B.whomever C..on whom D.in which
3、Anyone ______ has been to China thinks highly of the Great Wall.
A. whom B. who C. whose D. as
4、The meeting was a greet success,（ ）everybody was free to give their opinions.
A.where B.which C.that D.on which

Answer 1

1.B 2.C 3.B 4.A
1.of表示所属，后面的company是个名词，所以前面要用形容词形物主代词whose
2.depend...on sb,on是介词，后面跟宾格whom
3.who在从句中作主语，所以用主格
4.非限制性定语从句，where=in which. D选项介词用错了