怀疑

I doubt greatly that this plan will work.

I doubt if/whether he will come.

take a sceptical attitude

I suspect that this 100- yuan note is a counterfeit.

suspect sb of telling lies

I have some doubt/suspicion about her motives.

have a slight suspicion

be above/beyond suspicion

be under suspicion

entertain/harbour a suspicion; have one's suspicions

remove doubts; allay/dispel suspicion

strengthen one's suspicion

feel doubt

doubts appear/arise; a doubt comes to one's mind; cast/throw doubts on

express doubts; voice (a) doubt