we were worried about was they could manage to control the pollution.
A. That; how
B. That; whether
C. What; that
D. What; whether
网友回答
A. That; how
B. That; whether
(答案→)C. What; that
D. What; whether
解析：
这题考查名词性从句的用法,what引导的是主语从句，what在主语从句中做宾语，that引导表语从句，在从句中不做成分。句意是：我们担心的是,是否他们能设法控制祝污染。