13:45 it is a quarter to two.
12:00 it is twelve o'clock.
16:45 it is a quarter to five.
17:30 it is half past five.
12:55 it is five minutes to one.
20:15 it is a quarter past eight.
19:10 it is ten minutes past seven.
20:25 it is twenty five minutes past eight.
21:10 it is ten minutes past nine.