Must be the correct modal verb in each case. -Look at that old car, I wonder how much it costs. It must be expensive, it’s in very poor condition. -where’s mum? I’m not sure. she might be home because her bag is here. She might be in the kitchen, or she might be in the garden. - Khalid isn’t at work today. He must be ill.

1. Modal verbs

2. Modal verbs
The modal verbs include can, must, may, might,
will, would, should. They are used with other verbs
to express ability, obligation, possibility, and so on.
Below is a list showing the most useful modals and
their most common meanings:
Modal Meaning Example
can to express ability I can speak a little Russian.
can to request permission Can I open the window?
may to express possibility I may be home late.
may to request permission May I sit down, please?
must to express obligation I must go now.
must to express strong belief She must be over 90 years old.
should to give advice You should stop smoking.
would to request or offer Would you like a cup of tea?
would in if-sentences If I were you, I would say sorry.

4. Modals of Certainty in the Present
1.Must: strong degree of certainty (we are almost sure something is true(95%)
and we have reasons for our belief.
Example
John must be very tired, he’s been staying in bed all day long.
They must be absent, I can’t find them anywhere.
2. can’t : we’re sure somthing isn’t true (impossible ) and we have reason for our
belief.
Example
Jack can’t be at school, I saw him playing basketball at the playground.
Ali can’t be in Spain because I saw him driving past my house this morning.

5. Possibility: may, might, could
May / might: express a weak degree of certainty( less sure 50%) remote possibility.
(perhaps/ possible/guess/not sure, I don’t know, maybe)
Example
There are no clouds in the sky but it might rain.
Don’t swim here , you might be attacked by shark.
Oh dear! we’re a bit late. We might miss the bus.
(there’s a possibility that something may happen but no one is very sure)
Could: express strong probability(likely to happen)
-you need your calculator for your maths homework. It could be in your school bag.
-Extreme rain could cause the river to flood the city.
We rarely use might in questions about possibility
Someone’s coming .Who could it be? We use could .

7. 1: Talking about the present:
must / might / could / may / can't + infinitive
•For example:
I am waiting for Julie with another friend, David.
I ask: 'Where is Julie?'
David :She must be on the bus. (I'm fairly sure this is a good guess)
•She might come soon. (maybe)
•She could be lost.
•She may be in the wrong room. (maybe)
•She can't be at home. (I'm fairly sure this isn't true)
Notice that the opposite of 'must' is 'can't in this case.
.

8. 2: Using modal verbs to talk about the past:
must / might / could / may / can't + have + past participle
•(Click here to review how to make the past participle)must have + past
participle
•might / might not have + past participle
•could / couldn't have + past participle
•may / may not have + past participle
•can't have + past participle
•For example:
You: Where was Julie last night?
David: She must have forgotten about our date.
•She might have worked late.
•She could have taken the wrong bus.
•She may have felt ill.
•She can't have stayed at home.

9. Choose the correct modal verb
-Look at that old car, I wonder how much it costs. It (must/ can’t) be
expensive, it’s in very poor condition.
-where’s mum? I’m not sure. she (might/must)be home because her
bag is here. She (might/can’t)be in the kitchen, or she (might/must) be
in the garden.
- Khalid isn’t at work today. He (must/can’t) be ill.