By the time he realizes he _____ a mistake, it’ll be too late for him to change his mind.
Children often get presents ___ Christmas and ___ their birthdays.
You can find the new hospital ___ the end of the street.
___ the end of this new term we'll have graducated from middle school.
The mid-term exam is to be held ___ the end of this month.
I’ll be free ___ seven o’clock.