long

go on, keep, observe
All members of the religious community keep these fasts.

break
In the evening the people break their fast.

be, seem
Her pulse seemed very fast.

extremely, fairly, very, etc.
I suppose delivery in two days is pretty fast, really.
I should make a very fast profit on these.

awfully, exceptionally, particularly, remarkably, surprisingly
reasonably, relatively
a little, slightly, etc.
amazingly, blazingly, blindingly, impossibly, incredibly, unbelievably, unusually
He came around the corner blindingly fast.

dangerously

Fast is used with these nouns:
acceleration, access, bowler, bowling, car, computer, current, dance, delivery, descent, exit, film, food, friend, gallop, growth, horse, lane, lap, learner, link, modem, pace, passage, progress, pulse, rate, reaction, reactor, reader, recovery, reflex, relief, return, rhythm, road, route, runner, service, speed, stretch, stroke, tempo, time, track, traffic, train, trot, turnover, typist, walk, worker

Fast is used with these adjectives:
asleep, stuck

Fast is used with these verbs:
approach, beat, breathe, change, decline, drive, drop, dwindle, expand, fade, fill, flow, fly, grow, pedal, progress, recede, recover, ride, rise, run, shrink, sink, spin, spread, think, travel, update, walk