Question

__________for the bus, I heard a noise,

A．While waiting

B．While I waiting

C．I was waiting

D．Waited

Answer 1

A

考查状语从句的省略式，英语中的主从句的主语一致时，可以省略从句的主语和be动词，while waiting="while" I was waiting，句意是：当我等汽车的时候，我听到一生噪音。选A。