svp c'est exercice merci

ex4:
a. she can't be your sister
b. he might have something to say to you
c. she might be too young to understand
d. she can't be living in this flat

ex5
a.she may have missed the train
b. she must have forgotten
c. you might find another flat
d. she can't be thinking of you

ex6
a. he must have recognised you
b. it can't be possible that he's that late
c.she may be waiting for us
d. they must have left earlier