Collocations for certain - adj.

be, feel, look, seem
Digby looked certain to be the next president.

become, grow
I grew more and more certain that she was lying to me.

make
Make certain that you lock the door if you go out.

very | absolutely, quite | by no means
It''s by no means certain that she''ll get the job.

almost | fairly, pretty

about/of
Are you quite certain about this?

can''t/couldn''t say for certain
I think she''s a teacher, but I couldn''t say for certain.

not know for certain
I don''t know for certain how many people are coming.