问题
选择题
Everyone here will thank the firefighters for the things they have done to prevent fires _______ the environment safer.
A．make
B．to making
C．to make
D．from making
答案
答案：C
从语法角度考虑可排除A、B两项，D项符合语法，但句意不妥，C项不定式结构表结果。