Réponse:

1) I may be wrong

2)you may not agree with me

3)they must be waiting for us

4)she may not be at home

5)she must be older than her husband

6)we may go to Scotland next summer

7)it may not rain tomorrow

8)he must be very good at languages

9)he may not be the murderer

10)she may not get our letter in time

11)there must be a service station in the village

12)there may be a mistake somewhere