Must / can't - to express probability in the present
Structure: modal + infinitive without to must be, must have, can't go, etc.
We use must to express that we feel sure that something is true.
They are really good, they must win. They must be very rich. Look at the house.
We use can't to say we are sure that something is impossible.
She can'tbe ill. I've just seen her in the shop and she looked fine. It can'tbe true. I don't believe it.
May / might / could - to express probability in the present
Structure: modal + infinitive without to may be, might do, could go, etc.
We use may or could or might to say that it is possible that something will happen or is happening.
They may be arriving tomorrow. He might be away on holiday. He could be away on holiday. He mightbe offered the job.
The negative of may is may not.The negative of might is might not. They both mean that it is possible that something will not happen or is not happening.
We DO NOT use could not to express probability.
He might notbe offered the job. I may notpass the exam. I might notgo to the match tomorrow. I could not go to the match tomorrow.
Example: Someone is knocking on the door. I’m sure it’s my brother – he promised to come today. Someone is knocking on the door. It must be my brother – he promised to come today.Top of Form
1. I'm sure he is here - I can see his car in front of the building. He_____________ be here. I can see his car in front of the building.
2. They're coming this week but I don't know which day. They ______________ be coming tomorrow.
3. I'm not sure I'm going to pass the exam. I don't feel very confident. I _______________ pass the exam. I don’t feel very confident.
4. I've bought a lottery ticket. There's a chance I'll become a millionare!
I __________________ become a millionare!
5. I'm sure she doesn't speak French very well - she's only lived in Paris for a few weeks. She __________________ speak French very well. She’s only lived in Paris for a few weeks.
6. My key's not in my pocket or on my desk so I'm sure it's in the drawer. My key's not in my pocket or on my desk so it ________________ be in the drawer.
7. Someone told me that Mark was in Mexico but I saw him yesterday so I'm sure he's not abroad. Mark ______________ be abroad.
8. You got the job? That's great. I'm sure you're delighted. You got the job? That's great. You ________________ be delighted.
9. They told me to prepare the project by tomorrow but it's alomost impossible to have it done so fast. I _______________ finish it by tomorrow if I stay at work all night, but I'm not sure.
10. I asked them to send the goods as soon as possible; we _____________ receive them by the end of the week if the post is fast.
