It was possible that she was taking a shower, which is why she could not hear the bell
may
She .................... shower, which is why she could not hear the bell
I am sure he hasn't left because his coat is still here
have
He .................... because his coat is still here
The ferry could not sail because the weather was bad
due
The ferry could not sail .................... weather
The teacher told us not to be late on Friday
better
'You .................... late on Friday', the teacher said
There are Spanish and French translation of the book
been
The book .................... into Spanish and French
She will only phone if she gets lost
unless
She will .................... lost