There could be no doubt about it.
There won’t be an election in June
There must be a mistake.
There can’t have been any doubt about it.
There might have been a strike.
There oughtn’t to have been any difficulty about it
There can’t be anyone waiting outside.
There never used to be anyone living next door
There could be something blocking the pipe
There might have been someone waiting outside.
There must have been something blocking the pipe
There could have been someone crossing the road.