4th+year+grammar


 * Function || Modals || Notes || Examples ||
 * Obligation / necessity || must

have to

don’t have to || **Must** expresses **//necessity//** in writing (official forms, signs, manuals) When must is used in spoken English, the speaker: - is usually in position of power

- is expressing urgent necessity


 * Have to** is used in conversation and informal writing

describes a lack of necessity in the present || You **must** answer all the questions.

You **must** go to beв right now, Tommy! (mother talking to her child) You **must** see a doctor about that cough.

You **have to** go there.

They **don’t have to** leave the house. (It isn’t necessary for them to leave; if they wish, they can stay) ||
 * **Future obligation** || **will have to**
 * will need to**


 * will not have to**
 * will not need to** || describe a lack of obligation in the future || There’s an admission charge so we’**ll have to** take some money with us.

They’re going to give us lunch so we **won’t need to** take any food. || ought to || should is more formal than ought to || You **should** watch the news tonight. Terri **ought to** watch it too. || I **ought to have taken** that job! ||
 * Advice || should
 * **Advice about past** || **should have done**
 * ought to have done** ||  || I **shouldn’t have said** that!
 * Prohibition || mustn’t

can’t || a negative obligation in the future || They mustn’t leave the house. (They’re not allowed)

We should eat something now. You **can’t** take food into the theatre. || be able to || can is more common than be able to for present ability || She can sign, but she can’t dance. We aren’t able to complete this task. || She’s going on holiday so she **won’t be able to** see you next week. ||
 * Ability || can
 * **Future ability** || **will/ won’t be able to** || **__don’t use can__** for future ability || After I pass my driving teat I’**ll be able to** drive a car on my own.
 * **Past ability** || **could**
 * was/were able to**


 * was/ were able to/ could**


 * manage to**
 * succeed in doing** || to talk about a single action in the past

to talk about something you did that was difficult || When I was young I **could** run for miles without getting tired. Years ago people **were able to** drive without taking a test.

There was a bus strike, but I **was able to** get a lift with a colleague.

Our flight was cancelled but we **managed to** get seats on the next one. After several phone calls we **succeeded in** speak**ing** to the manager. || can’t/ couldn’t have to must not may may not might/ could might not || use **must/ have** to when you almost **100% certain** that something is **true**
 * Possibility || must

use **may**, **might**, **could** when you are **less certain**

use **can’t or couldn’t** when you are almost **100% certain** that something is **impossible**

use **must not** when you are slightly **less certain**

use **may not** and **might not** when you are **even less certain** || It **must** be 10 o’clock. The news just came on. This **has to** be a rerun. I’m sure I’ve seen that before.

He **may** be the murderer. He looks guilty. He **could** be home now. The lights are on.

They **can’t** be guilty. They weren’t even in the city when the crime occurred. They **couldn’t** own a gun. They hate violence.

You must not know them very well. You’ve only met them twice.

We may not have enough evidence. No one saw the suspect. || might could
 * Future possibility || may

might not/ could not || describes a negative possibility || In the future cars **might** contain high pressure hydrogen tanks. We **could** go to Greece next summer. They **may** be able to help you with the problem.

The weather forecast is good so we **might not** need our umbrellas tomorrow. ||
 * **Past possibility** || **may have done**
 * might have done**
 * could have done**


 * must have done**


 * couldn’t have done** || to express **speculations** or **possibilities** about a **past** situation. These speculations are based on **facts** that we have.

use **must have done** when you are almost **certain** about your **conclusions**

to express a feeling of disbelief or **impossibility** || Fact Archeologists found pictures of creatures with wings. Speculations Space beings **may have visited** that civilization. The pictures **might have marked** a landing strip for a spacecraft. The pictures **could have shown** mythological creatures.

Fact The Easter Island statues are made of stone. Conclusions The islanders **must have had** very sharp tools. The stone **must not have been** too hard for their tools.

He **couldn’t have believed** the space visitors helped them! It doesn’t make any sense. ||