Choose the correct modal verb to complete the sentences.
1.The vet said the dog was lucky.It could have lost/must have lost its leg
2.Candidates might/must be at the examination centre 15 minutes before the exam starts
3.The cleaner could break/must have broken the vase.she was cleaning this morning
4.Can/may he have been working so long?
5.You cant have seen/couldnt have seen Alice yesterday.she is away on holiday
6.She may have learned/can have learned english at school.