Modals of deduction: practice

I can’t find my text book. I had it this afternoon at work but it’s not in my bag now.	
My boyfriend promised to call me this afternoon but he didn’t!	
I’m worried about my grandmother. She never goes out but when I called her this afternoon, no one answered.	
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.	
I think my heart has stopped beating! I tried to feel my pulse this afternoon but I couldn’t feel a thing.	
When I came home from the pub last night, I put the key in my front door but it wouldn’t fit. I tried three times and in the end I had to sleep in the car.	
I’ve just got a telephone bill for HK$40,000. I only make local calls!	
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!	

I can’t find my text book. I had it this afternoon at work but it’s not in my bag now.	
My boyfriend promised to call me this afternoon but he didn’t!	
I’m worried about my grandmother. She never goes out but when I called her this afternoon, no one answered.	
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.	
I think my heart has stopped beating! I tried to feel my pulse this afternoon but I couldn’t feel a thing.	
When I came home from the pub last night, I put the key in my front door but it wouldn’t fit. I tried three times and in the end I had to sleep in the car.	
I’ve just got a telephone bill for HK$40,000. I only make local calls!	
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!	

Possible responses	

I can’t find my text book. I had it this afternoon at work but it’s not in my bag now.
You might have left it in the office.	
My boyfriend promised to call me this afternoon but he didn’t!
He could have been busy at work.	
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 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.	
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.	
When I came home from the pub last night, I put the key in my front door but it wouldn’t fit. I tried three times and in the end I had to sleep in the car.
You must have been drunk. You must have been trying to get into the wrong flat. 	
I’ve just got a telephone bill for HK$40,000. I only make local calls!
They must have made a mistake.	
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.