Question

In 1918, flu
(break) out among American troops stationed in France. It
(spread) through all the armies but (cause) few deaths. Four
months later, there (be) another outbreak, which (prove) to be
a killer.​

Answer 1

1. broke

2. spread

3. caused

4. was

5. proved

(Kindly note I have written all answers in simple past tense, as any specifications were not given in question.)