Modal verbs

In judo, you ............ kick your opponent.
1. can
2. mustn't
3. should
The sports centre opens at 13.00, so we .............. go swimming this afternoon.
1. can
2. must
3. shouldn't
You ...................... buy some new tennis balls. These are old.
1. can
2. should
3. mustn't
You ................ play football without a ball.
1. can't
2. must
3. shouldn't
You .................... play by the rules (reglas).
1. can
2. must
3. can't