Check – phrasal verb
Check in – to tell the official that you’ve arrived (at hotel, airport and such)
The passengers must check in 2 hours before the scheduled departure of the flight.
Check out – pay the bill in the hotel and leave
The guests are required to check out by 10am.
Check out – to be found to be true after examination
The police found that her story didn’t check out.
Check over – to examine something carefully
Check over you essay for mistakes before you hand it in.
Check up on – to find out that something is true or correct
The police checked up on my version of events.
Check up on somebody – make sure that the person is doing what he/she should
He’s gone to check up on his subordinates.