2) a - you shouldn't eat in the classroom
b- she can't speak English
c - we can watch TV after doing our homework
d - students have to learn there lesson
e - he can run 900 metres in 4 minutes

3) a - pupils have to revise before the exam
b- I can't speak German, I always get bad marks!
c -cheerleaders can sing and dance
d - we shouldn't listen to music in class
e - students have to learn the pledge of allegiance by heart
f - you shouldn't speak loudly at the library