Modals: deductions about the past

I thought I saw Sarah this morning but it _____ been her – she's in Scotland this week.

How did she fail that exam? She _____ studied very much.

He wasn't answering the phone before. Maybe he went to the shop or he _____ been in the shower.

I explained the homework but she did the wrong page. She _____ misunderstood me.

Wow! Have you finished all that already? You _____ been hungry!

Where's Clare? Her bag's here and her computer's still on so she _____ gone home.

I _____ left my wallet in the restaurant. I paid for the taxi home afterwards.

I think I _____ left the air conditioning on. Please can you check?

Oh, good! We've got milk. Mo _____ bought some yesterday.

Why were there no buses yesterday? Maybe it was the snow or they _____ been on strike.

Sorry, I don't know if she's here or not. She was feeling ill so she _____ gone home.

Oh no! My phone's not in my bag. I _____ left it at home.

It is still a mystery how the robber gained access to the bank. Police are investigating whether the suspect _____ known one of the employees.

You _____ seen her, surely! She was standing right in front of you.

Oh, great! His car's here. He _____ come home earlier than planned.

Let's ask at reception to see if they have your keys. Someone _____ found them.

I can't remember my password! But I _____ written it in my notebook as sometimes I do that.

She _____ cleaned the whole house on her own in two hours. She must have had some help.

He _____ known about it when I saw him. I'm sure he would have told me.

He _____ gone to Portugal. He didn't have a passport.