1.should
2. can't
3. mustn't
4.shouldn't
5.can't
6. can
B
1.My sister might lend me some money.
2.I can't open this jar.
3.My parents should probably let me go to the party.
4.I couldn't do the maths test.
5.You mustn't play football indoors.
6.The teacher may let me leave earlier.