if everyone makes a contribution __ the environment.

问题描述:

if everyone makes a contribution __ the environment.
our country will become more beautiful
a: to protect
b: to protecting
答案和具体原因

答案:B.to protectin
make a contribution to sth/doing sth.对.作贡献.
这是固定的句型,注意那个"to"是介词而不是不定式,介词后面要加动词或动名词.