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
C. What that
(答案→)D. What whether
解析：本题考查名词性从句。What引导主语从句，从句中缺少宾语，whether引导表语从句，句意：我们所担心的是他们能否成功的控制污染。选D。