1 My brother has to do the washing up every day.
2 We have to clean our classroom once a week.
3 To be a doctor you have to study for about six years.
4 You have to be seventeen to drive in Britain.(получается только так, если на первое место поставить In, то предложение не составить)
5 We sometimes have to use calculators in mathematics classes.
6 My mother has to leave the house at 6.30 every morning.
7 This party has to end at midnight because we have to get up early in the morning.