Come about – happen
- Nobody knows how these things came about.
Come across – find by accident
- On my way to market, I came across an old beggar.
Come upon – find by accident
Come of – have as a result
- What came of the discussion? (= What happened afterwards? What was the result?)
Come off – happen; take place
- The prize distribution ceremony will come off next week.
Come to – happen to
- How did you come to hear of it?