We must ________ any pollution ________ more happily．
A.prevent; from livingB.stop; livingC.prevent; to liveD.keep; living在线课程C
解析：
prevent any pollution阻止污染，注意不要与prevent sb．from doing sth．的结构混淆，该结构中的doing sth．在句中作介词from的宾语，而to live more happily是目的状语。