I think the environment is becoming worse and worse.Yes I really don’t know we ca

问题补充：

--- I think the environment is becoming worse and worse.

--- Yes, I really don’t know we can do about it.

A. which

B. whether

C. that

D. what

答案：

A. which

B. whether

C. that

(答案→)D. what

解析：词义辨析。Which哪一个；whether是否；that那个；what什么。句意：我认为环境变得越来越差了。——是的，我们真的不知道关于这事我们能做什么。下文宾语从句中缺少逻辑宾语。故选D。