Come across = find/meet by chance
Come by = obtain
Come down to = be passed on to sb by inheritance
Come down with =become ill; go down with
Come into= inherit
Come off=succeed
Come out =1.(of flowers) begin to blossom 2.be published 3.(of stains) be able to be removed
Come round =1.visit casually 2.recover consciousness
Come to amount to a total
Come up = be mentioned 2.arise;occur
Come up to = 1.approach 2.equal;(of expectations) be up to
Come up with =find(an answer, solution, etc)