Phrasal verbs

  drop out (to withdraw or to stop participating in something) He decided to drop out of college to start a business. Because of a foot injury, he had to drop out of the race.     envocabulary.com    

  drop by  informal (to visit briefly) We decided to drop by his club to see if he was there. I’ll drop by the store to pick up some food on my way home.     envocabulary.com    

  drop in informal (to visit someone unexpectedly) You’re welcome to drop in whenever you wish. I might drop in for a chat this afternoon.     envocabulary.com  

  drop back (to move or fall to a lower position) Mike was in the lead but has now dropped back to third place. My business’s revenue has started to drop back to previous levels. It would be too costly for us to drop behind our competitors. Also: drop behind …

  go back (return to a place) I must go back; I have left the door unlocked. It is getting dark; we should go back home. (to have existed since a time in the past) Their friendship goes back to when they were neighbors. Some of these buildings go back to the …