Question

Although ___ very hard,he failed to start his car. A.worked.

Answer 1

C 这是一个状语从句的省略,原则是：从句的主语和主句的主语一致,并且含有be动词.如果主语和动词之间构成主动,则用v-ing.如果主语和动词之间构成被动,则用过去分词表示被动.

主动v-ing ,被动用v-ed.

加油!