Present/Past speculations

I'm sure that's our plane.That ----------- be our plane.

It's possible that's our dog. That ________ be our dog.

We're sure that isn't our bill. That__________  be our bill.

It's possible this is the hotel. This _________  be the hotel.

I'm sure that isn't our baggage. That  be _______ our baggage.

They only set off half an hour ago. I'm sure it's not true that they have arrived already.

It is possible that Alice brought some sun cream. She's so pale-skinned.

She can't find her passport! I'm sure it's true that she left it in the hotel room.

I'm sure you are tired. We've been walking and sightseeing all day.

It's possible that's our taxi. That ______   our taxi.