1 . The Zhuang is an ethnic group________ the population is the largest of all ethnic groups in China.

A．of whom

B．of which

C．of who

D．of that

2 . Human facial expressions differ from those of animals in the degree ______ they can be controlled.

A．on which

B．by which

C．to which

D．from which

3 . 他处理这个问题的方法是有效的。（prove）(汉译英）

4 . 园艺使人们得以侍弄花草，通过与大自然的接触得到美的享受，能修身养性。(which) (汉译英)