Rearrange the parts to make a meaningful sentence.

P. was put out did

Q. only after the fire

R. the cause of the blast

S. the firemen find

Explanation

1. 01

   "Only after" at the start turns the main clause round: Q, then P "was put out", followed by "did".

2. 02

   "Did" is followed by the subject and a plain verb: S "the firemen find", and R says what they found.

3. 03

   So the order is QPSR: "Only after the fire was put out did the firemen find the cause of the blast."