A. in = into a room, a building, a car etc. (e.g. How did the thieves get in?)
A1. in the same way you can say go in, come in, walk in, break in etc.
A2. I’m moving in next week. vs. I’m moving into my new flat on Friday.

B. drop in/ call in = visit somebody for a short time without arranging to do this. (e.g. I dropped in to see Bob on my way home)
B1. Joint in = take part in an activity that is already going on. (e.g. We’re playing a game. Why don’t you join in?)
B2. Plug in an electrical machine = connect it to the electricity supply. (e.g. The fridge isn’t working because you haven’t plugged it in)
B3. Fill in a form, a questionnaire = write the necessary information on a form. (e.g. Please fill in the application form and send it to us by 25 April) (= fill out)
B4. take somebody in = deceive somebody (e.g. The man said he was a policeman and I believed him. I was completely taken it)

C. out = out of a room, building, a car etc. (e.g. He just stood up and walked out)
C1. In the same way you can say go out, get out, move out, let somebody out etc.
C2. He walked out. vs. He walked out of the room.

D. eat out = eat at a restaurant, not at home (e.g. There wasn’t anything to eat at home, so we decided to eat out)
D1. drop out of college/ university/ a course/ a race = stop before you have completely finished a course/ race etc. (e.g. Ken went to university but dropped out after a year)
D2. get out of something that you arranged to do = avoid doing it. (e.g. I promised I’d go to the wedding. I don’t want to go, but I can’t get out of it now)
D3. cut something out (of a newspaper etc.) (e.g. There was a beautiful picture in the magazine, so I cut it out and keep it)
D4. Leave something out = omit it, not include it (e.g. In the sentence ‘She said that she was ill’, you can leave out the word ‘that’)