Choose the correct particle. keep away: prevent access to, hold back keep off: stay away, prevent from stepping/climbing on sth keep on: continue keep up with: move at the same speed let down: disappoint let out (of): release (from prison/ captivity) pick on: treat unkindly pick out: choose pick up: 1) lift with hands 2) take someone away in a car 1 Please keep off/away the grass! 2 Don't worry. Anna will never let you out/down. 3 The girls kept up with/on talking. 4 Mark has just been let out/down of prison. 5 l'll pick you up/out at 7:00 at the airport.