The earth will become worse and worse we do something to stop her from being polluted.A.

问题补充：

The earth will become worse and worse we do something to stop her from being polluted.

A. if

B. even if

C. when

D. unless

答案：

A. if

B. even if

C. when

D. unless

解析：考查连词辨析。 If 如果；ever if 即使；when 当。。时候；unless除非。句意：除非我们做一些事情来阻止它被污染否则地球会变得越来越糟糕。Unless 相当于 if not ,根据题意可知，这是个条件句，所以选D项。