Complete the sentences with the correct form of the verbs in brackets. Use the correct past modals of deduction.
1 I’m not sure why he wasn’t at home.
He _________________ (go) out for a walk with his dog.
2 You _________________ (see) my brother at school yesterday. He has been away since last week.
3 Wow! Your dress looks really expensive!
It _________________ (cost) a fortune!
4 My brother _________________ (have) an argument with his girlfriend. He looks really upset.