Question

While________ along the road, Mr. Smith met an old friend of his.

A．walked

B．he is walking

C．walking

D．is walking

Answer 1

C

解析试题分析：考查状语从句及其省略。句子可还原成由while引导的时间状语从句，While he was walking along the road, Mr. Smith met an old friend of his.故B错误在is应改成was。状语从句的省略是指省略从句的主语和部分谓语，即省略he was，故选C
考点：考查状语从句及其省略。