We use the modal verbs can't/couldn't, must and must not if we are MORE SURE about the fact or the speaker has much more confidence in what is being said. (True, False)

The house is huge, so it _____ have belonged to the royal family. (must, could)

We use the modal verbs could/might and might not if we are LESS SURE about the fact or the speaker is just guessing. (True, False)

There are bedrooms in the building, so it ____ have been a temple. (might not, couldn't)

The lost treasure ______ be in a cave. (could/might, must)

No one's ever found it. It _____ exist. (must not, might not)

However, it _____ have belonged to an important person at all. (might not, must)

But the treasure _____ even exist. (couldn't, might not)

This house _______ have belonged to the royal family. (could/might, must)

It ______ be in that cave. It's too high. (could/might, can't/couldn't)

There are many jewels on this necklace. It ____ be very valuable. (might, must)