| Question   | Answer   | 
        
        |   You could have left it in the café.   start learning Use modal verb + have + past participle |  |   Use modal verb + have + past participle to make deductions or guesses about past actions or states.  |  |  | 
|   She must have been feeling ill.   start learning Use modal verb + have + been + -ing form |  |   Use modal verb + have + been + -ing form to make deductions about continuous actions or states.  |  |  | 
|   It can't have been stolen from your bag.   start learning Use modal verb + have + been + past participle |  |   Use modal verb + have + been + past participle for deductions using the passive.  |  |  | 
|  start learning I must have deleted the email. I can't find it anymore.  |  |   you are almost certain that something is true, based on the evidence    have + past participle (the perfect infinitive) is also used with other modals: should have (been) and would have (been) |  |  | 
|  start learning The plane could have been delayed by the weather. There's a bad storm at sea.  |  |   you think it is possible that something is true, based on the evidence    have + past participle (the perfect infinitive) is also used with other modals: should have (been) and would have (been) |  |  | 
|  start learning It can't have been the waitress. She wasn't in the room when the bag was stolen.  |  |   you are almost certain something is not true or is impossible, based on the evidence    have + past participle (the perfect infinitive) is also used with other modals: should have (been) and would have (been) |  |  | 
|  start learning To speculate or make a deduction about something that happened in the past,  |  |   use the modals: must/could/might/can't/couldn't + have + past participle    It can't have been the young couple because I was looking at them all the time. |  |  | 
|  start learning To emphasise that an activity was in progress,  |  |   use modal + have + been + -ing    The woman must have been working with the guy. |  |  | 
| start learning |  |   use modal + have + been + past participle    So it must have been stolen when I was taking the photo. |  |  | 
|   Perhaps Jenna while we were out. Let me check on the answerphone.   start learning must/might/may/could/ can't/ couldn't have |  |   Jenna might have phoned while we were out.  |  |  | 
|  start learning Knock louder. You know he's a bit deaf. I'm sure he didn't hear you.  |  |   He can't/couldn't have heard you.  |  |  | 
|  start learning I locked the door. I'm certain. Maybe the thieves got in through the windows.  |  |   The thieves might/could /may have got in through the window.  |  |  | 
|  start learning I can't find the final version of the report in my computer. I realised it was impossible that I saved the document.  |  |   I realised I couldn't have saved the document.  |  |  | 
|  start learning Ooh, that was a bad knock to your head. I'm certain it hurt a lot.  |  |  |  |  | 
|  start learning I don't know why Wanda was late for the meeting. Maybe her plane was delayed.  |  |   Her plane might/could/may have been delayed.  |  |  | 
|  start learning I'm sure I've made a mistake. The date looks wrong.  |  |   I must have made a mistake.  |  |  | 
|  start learning Paola should have won the race. It's impossible that she was trying hard enough.  |  |   She can't/couldn't have been trying hard enough.  |  |  | 
|   Look at her necklace. Are those real diamonds?   start learning Yes. It (?) a fortune! (cost) |  |   Yes. It must have cost a fortune!  |  |  | 
|   I tried phoning Mike four times but he didn't answer.   start learning He (?) his phone or maybe he left it at home. (switch off) |  |   He might/could/may have switched off his phone or maybe he left it at home.  |  |  | 
|   Why was Danielle in the office at midnight?   start learning She (?) late. She had a big meeting the next day. (work) |  |   She must have been working late. She had a big meeting the next day.  |  |  | 
|   I'm sure Len told me you were a doctor.   start learning He (?) of my sister, Rachel, or maybe he confused me with someone else. (think) |  |   He might/could/may have been thinking of my sister, Rachel, or maybe he confused me with someone else.  |  |  | 
|   I've lost my boarding card. It's not in my bag!   start learning You (?) properly. I saw you put it there just now. (look) |  |   You can't/couldn't have looked properly. I saw you put it there just now.  |  |  | 
|   Do you think Yves knows he didn't get the promotion?   start learning I suppose he (?) by the boss but I doubt it. (tell) |  |   I suppose he might/could/may have been told by the boss but I doubt it.  |  |  |