to say that one is not satisfied, that something is wrong, that one is suffering

grumble about

to deny the truth of (something said or written, a person who has given a decision etc)

be at variance with

to act in opposition to( a low, a custom)

go against, contradict

to say that (something) is not true

disagree, renounce, decline

to say that one does not own for have a connection with (a person, thing, action etc)

deny

to be, fight, against (a person, organization, plan, idea etc)

fight, obstruct

to prove (a person, statement, opinion etc) to be wrong or mistaken

prove false; discredit