They ___ be on holiday but I'm not sure.
may/might
When you_____(tell) that scary story, I_____(hear) a loud noise in the garage.
When you were telling that scary story, I heard a loud noise in the garage.
Frank knows how to stand on his head. = Frank ___ stand on his head.
can
I don't care what you_____(do), I want to know why she_____(steal) my bag.
I don't care what you were doing, I want to know why she stole my bag.
We ___ recycle our paper and plastics.
should
His dog_____(bark) while he_____(whistle) a song.
His dog was barking while he was whistling a song.
While Joseph _____ (study) yesterday the lighting _____ (strike) the tree in the garden.
While Joseph was studying yesterday the lighting struck the tree in the garden.
You ____ smoke here. It's forbidden.
mustn't
While Sara ______ (read) the doorbell ____ (ring)
While Sarah was reading, the doorbell rang.
'What kind of bird is that?'
'I'm not sure. It __________ be an eagle but I can't see it very well.'
might
_____ you _____ (listen) while he ______ (talk)?
Were you listening while he was talking?