Answer :
Answer:
51.I will leave the party earl because i must study for my exam.
52.I late last night because i mustn't go to school on Sunday
53.We ought not to play football as it's raining outside
54.You mustn't to drive a car if you don't have a driving licence
55.If you want some useful advice ,you must have better talk to your parents about your probem.
Explanation: