用can,may,must,can't,mustn't填空.

用can,may,must,can't,mustn't填空.
1.---_____you skate on real ice?
---No,I can't.
2.You_____play on the road .It's very dangerous.
3.---Who's that man?
---He_____be our English teacher.Our English teacher has gone abroad.
4._____I borrow your bike?
5.You_____listen to your teacher carefully in class.
6.We_____cross the road if the traffic is busy.
7.---Where_____my brother be?
---He_____be in the classroom,because I saw him in the library just now.
8.Students_____copy others' homework.
急