the fire broke out three fire-engines were rushed to the spot.A. HardlyB. QuicklyC. Imme

问题补充：

the fire broke out, three fire-engines were rushed to the spot.

A. Hardly

B. Quickly

C. Immediately

D. Gradually

答案：

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。