Idioms

Call it a day - stop working for the day; go home
Call off - cancel
Call on - visit
Calm down - relax
Care for - take care of - like; feel affection for
Catch on - become popular
Catch on (to) - understand, learn
Catch up (with) - go as fast as; catch
Check in (or into) - register (at a hotel)
Check out (of) - leave (a hotel) - take material (from the library)
Cheer up - become cheerful; be happy
Chip in (on-for) contribute
Clear up - clarify; make understandable - become nice&sunny (weather)
Come across - find; meet; encounter
Come around (to) begin to change one s opinion; begin to agree with
Come down with - become sick with (an illness)
Come up with - think of (an idea)
Cost an arm and a leg - be very expensive
Count on - depend on; rely on; bank on
Count out - eliminate; no longer consider as a factor
Cut off - stop; discontinue (a service)
Cut out for - have an aptitude for; be qualified for