Modal verbs. Logical assumption, possibility and probability.

must  I’m sure/certain that sth is true

Must is used in affirmative sentences and expresses positive logical

assumptions.

It is Sunday. He must be at home. (I’m sure he is at home.)

 can’t/couldn’t  I’m sure that sth isn’t true, real, etc.

Can’t and Couldn’t are used in negations and expresses negative

logical assumptions.

It is Sunday. He can’t/couldn’t be at work. (I’m sure he isn’t at work.)

 can  present infinitive  general possibility – it is theoretically

possible.

This structure is used in affirmative sentences to show that

something is possible theoretically or in general, that is when we are

not referring to a specific situation.

This road can be very busy. (In general, not in a specific situation.)

 could/may/might present infinitive  it is possible /it is

likely / perhaps

It is used to show that something is likely to happen in a specific

situation.

The roads could/might/mayget very busy tomorrow afternoon because

there is a demonstration (NOT: The roads can get ...)

 could/might  perfect infinitive (refers to the past)  it was possible,

but it didn’t happen.

Yesterday, I left the car unlocked. It could/might have been stolen, but

luckily it wasn’t.

 should/ought  probably

Should and ought are used to express that something is likely to happen in the present or in the future.

It’s 10 o’clock. He shouldbe /ought to be at work

Exercise 16.

Answer the questions in A using must or can’t., give a reason from B.

Example:

Are they Greek? - They can’t be Greek. They speak Italian.

A		B
Are they Greek? Is he ill? Is he eating on? Are they asleep? Is he happy? Is he a doctor?		It’s very cold in here. He’s too young. She’s just passed her driving test. They’re speaking Italian. Their bedroom lights are off. He’s got a high temperature.

Saying how sure we are

Exercise 17.

Find the correct place in the table for the words in the box.

might should must may ought to can’t could

YES NO

definitely _______ probably should; _______ possibly may; ______ ; ______ definitely not ______

Where’s Mr Mason?

He might be in his office.

He must be in his office.

He may be in his office.

He should be in his office.

He could be in his office.

He ought to be in his office.

He can’t be in his office.

Exercise 18.

Study these examples:

I’m sure she knows him well	present inf.	She must know him well.
It is possible that he’s working late tonight. I’m sure she’ll be working tomorrow.	present cont. inf.	He could be working late tonight. She must be working tomorrow.
I’m sure he didn’t know the truth. Perhaps they have missed the bus. It’s possible he had got lost.	perf. inf.	He can’t have known the truth. They might have missed the bus. He may have got lost.
I’m certain he was sleeping. Perhaps she has been lying. It’s likely they had been hiding.	perfect cont. inf.	He must have been sleeping. She may have been lying. They could have been hiding.

Exercise 19.

Rephrase the sentences using the correct form of the words in brackets.

Examples:

I’m sure she is in bed.. (must) - She must be in bed.

We’ll probably arrive before 11 o’clock. (should) - We should arrive before 11 o’clock.

Perhaps he was ill. (may) - He may have been ill.

It’s impossible that they missed the plane. (can’t) - They can’t have missed the plane.

1. Perhaps she’ll phone later. (might)

2. I’ll probably be at home by 6 o’clock. (should).

3. Perhaps they went home. (could)

4. It’s impossible that he’s telling the truth. (can’t)

5. I’m sure you’ve heard the news. (must)

6. Perhaps I won’t go out this evening. (may)

7. It’s impossible that she saw us. (can’t)

8. I’m sure the bus has left. (must)

9. Perhaps he didn’t apply for the job. (might)

10. She’ll probably be here soon (ought to)

Exercise 20.

Complete the sentences using must or can’t, as in the example

Example:

I’m sure she has gone on holiday.

She .....

She must have gone on holidays.

1. I’m certain he doesn’t know the secret.

He .............................................................

2. I’m certain Mike hasn’t got a new car.

Mike ..........................................................

3. I’m sure Susan has paid the phone bill.

Susan ........................................................

4. I’m sure they don’t live here.

They ..........................................................

5. I’m sure they left the party early.

They ...........................................................

6. I’m certain he didn’t call me.

He ...............................................................

7. I’m certain Marie sent you a birthday card.

Marie ...........................................................

8. I’m sure she has been keeping secrets from me.

She ..............................................................

9. I’m sure David didn’t go to the supermarket.

David ...........................................................

10. I’m certain he is working at the library.

He .................................................................

Exercise 21.

Translate the following sentences into English using suitable modal verbs.

1. Мне пойти и узнать, сделал ли он работу, Он, должно быть, сделал её вчера.

2. Тебе долго пришлось дожидаться его,

3. Зря я пришёл. Собрание отменили.

4. Ты должен был сказать нам об этом, а то теперь мы не знаем, что делать.

5. “Неужели она забыла заказать нам номера в гостинице?” – “Она , наверное заказала их на ваше имя.”

6. Не может быть, чтобы она сделала такую глупость.

7. Он должен приехать пятичасовым поездом. Неужели он опоздал на него?

8. Он, наверное не сказал им об этом, и они, наверное, не придут.

9. Он мог бы хотя бы что-нибудь сказать, чтобы поддержать меня.

10. Ты мог бы сказать, что опоздаешь.

11. К сожалению, я не смог поговорить с менеджером. Мне следовало позвонить о договориться о встрече заранее.

12. Тебе следовало бы еще раз прочитать своё сочинение. Там, наверное, есть ошибки.

13. Зря ты так разговаривал с ним. Он мог обидеться.

14. Не может быть, чтобы он забыл о своём обещании.