~のだろう (probably the case)

Now the tab is finally coming due.

If war were to break out, what would become of us?

If you were to die, I wonder what would become of your family.

She probably set things up so you'd end up resenting your friend.

What could she possibly be so sad about?

I wondered where she had dropped her wallet.

I tried to think about what the reason was that I didn't trust him.

It must have rained during the night. The road is wet.

I wonder what she's worried about.

I wonder where she studied English conversation.

It must have rained during the night.