помогите написать предложения в прошедшем и в будущем времени
1) I must do my exercises
2) He must at the institute at nine o'clock
3) You must learn the story by heart
4)we must wolk fast to get to the station in time
5) she must do at it once

I did my homework(past)I will do my homework (future)He will be at the institute at nine o'clock He was at the institute at nine o'clock