1.
When you ~, you go to bed. (INFORMAL)
Would you like some tea before you ~?
PHRASAL VERB: V P
2.
If you turn someone in, you take them to the police or tell the police where they are because they are suspected of committing a crime. If you turn yourself in, you go to the police because you have been involved in a crime.
He has been given until noon today to turn himself in to authorities...
There would be strong incentives to turn someone in...
I might today hesitate to ~ a burglar.
PHRASAL VERB: V n P to n, V n P, V P n (not pron), also V P n (not pron) to n
3.
When you ~ a completed piece of work, especially written work, you give it to the person who asked you to do it.
Now we wait for them to ~ their essays...
I want everybody to turn a report in.
= hand in
PHRASAL VERB: V P n (not pron), V n P
4.
If you turn something in, you return it to the place or person you borrowed it from. (mainly AM)
I went back to the station-house to ~ my badge and gun...
= return
PHRASAL VERB: V P n (not pron)