the fire broke out, three fire-engines were rushed to the spot.
A. Hardly
B. Quickly
C. Immediately
D. Gradually
网友回答
A. Hardly
B. Quickly
(答案→)C. Immediately
D. Gradually
解析：这四个选项都是副词：A. Hardly几乎不，B. Quickly很快，C. Immediately立刻，D. Gradually逐渐地，但是immediately也可以做连词“一…就…”，引导时间状语从句，句意：火灾一爆发，三个消防队员就冲到现场。所以选C。