He went home for lunch the clock struck twelve.
A. while
B. immediately
C. right away
D. at once
网友回答
A. while
B. immediately
C. right away
D. at once
解析：immediately除了用作副词之外,还可用作从属连词, 引导时间状语从句,相当于as soon as。有类似用法的词或短语还有: directly, the moment, the instance, the minute等。