Certain it happened
A girl walks into class late without talking to anyone.
• She gives a piece of paper to the teacher.
• She’s missing a tooth.
She must have been to the dentist.
I can’t find my textbook. I had it this afternoon at work but it’s not in my bag now.
You might have left it in the office.
Where's Clare? Her bag's here and her computer's still on so she _____ gone home.
can't have
• A boy arrives home looking tired.
• He has some interesting presents for his friends.
• He has a lot of luggage.
He must have been on holiday.
My boyfriend promised to call me this afternoon but he didn’t!
He could have been busy at work.
She _____ cleaned the whole house on her own in two hours. She must have had some help.
can't have
• A woman arrives home and is angry.
• She asks to borrow her friend’s phone.
• She calls her bank and the police.
She must have been robbed.
I’m worried about my grandmother. She never goes out but when I called her this afternoon, no one answered.
She might have been asleep. / She may not have heard the phone ring.
I think my heart has stopped beating! I tried to feel my pulse this afternoon but I couldn’t feel a thing.
Your heart can’t have stopped beating. You can’t have taken your pulse properly - (you must have had your fingers in the wrong place.)
• A man walks into work looking angry.
• He’s holding a helmet.
• His bike is broken.
He must have crashed his bike.
I think I’ve been ripped off. I ordered a camera on mail order and sent off a cheque for a thousand dollars. That was six weeks ago and I haven’t heard anything.
It could have got lost in the post or they might be out of stock.
• A girl walks into the room looking happy.
• She’s holding a letter.
• She’s going to throw away her course book.
She must have passed her exam.
Oh my god, what am I going to do? As I was coming home last night about midnight, I saw my girl/boyfriend walking down the street with another man/woman!
It might have been his colleague. She might have run into a friend.