1.tom/live in flat нужно поставить used to

1. i must brush my teeth. - anyone, most likely some disobedient child.

2. i have to brush my teeth. - a patient of dentist's, a human with diseased tooth.

3. i must tidy my room. - anyone, most likely some disobedient child.

4.i have to tidy my room. - anyone, probably a child.

5. i must take the medicine. - someone with easy form of illness.

6. i have to take the medicine. - most likely, a regular patient

teenagers wear diferrent clothes. their style is depend of their subculture. for example hippies wear indian style dresses and flower in their head. punks wear clothes that shok their parents. ravers wears casual, comfortable clothes for free dancing! that's all!