before doing和before to do

before doing和before to do before doing与before do before doing sth 和 before you do sth,为什么? BEFORE DOING和AFTER before sb doing还是do sth before doing sth还是do sth what to do before breakfast. work harder than before,because i'm doing ___ i want to do.A long before 和before long before和before before doing sth help,open的过去分词是什么?是before sb do sth.还是before sb doing sth...