---Did they have a good time at the party?---Judging by their smiles, they _________ have enjoyed themselves.

---Look at the boy running on the playground. Is it David? ---It ______ be him. I saw him go to the teachers’ office just now.

I’m very glad I have my own room in my house. I ____ do all I like in it.

Every time she was in trouble, she went to him for help, as he said he   ________     do anything for her.

—Why are your eyes so red? You _______ have slept well last night.—Yeah, I stayed up late writing a report.