Answer:
a) No sooner had the firemen extinguished one forest fire than another started.
b) Never before had I been so petrified as when I did a parachute jump.
c) I suspect that only much later from now will we find out the cause of the explosion.
d) Little do we know at the moment where the ability to clone humans might lead.
e) Under no circumstances are passengers permitted to smoke on the flight.