often interchangeable. They are very common in spoken English. They have only one form; ought is always followed by the to-infinitive.
Should and Ought to express:
1. Mild obligation, moral or mild/weak duty, responsibility (in this meaning ought to is preferable).
should and ought to are less emphatic than must and have to:
with should the person has some choice on whether or not to act, but with must he has no choice.
Kit should apologise. (= it would be a good thing to do)
Kit must apologise. (= he has no alternative)
2. Advice, desirability, recommendation. (in this meaning should is more common).
We are talking about what is a good thing to do or the right thing to do: Luna thinks Kit should apologise to all the dogs.
3. Should (ought to) have + past participle can mean something that would have been a good idea, but that you didn’t do it. It’s like giving advice about the past when you say it to someone else, or regretting what you did or didn’t do when you’re talking about yourself.
Kit should have stayed with the dogs.
Shouldn’t (oughtn’t to) have + past participle means that something wasn’t a good idea, but you did it anyway.
He shouldn’t have run away.
EXERCISE 4
Chilly is keen on giving advice. Complete the sentences using the proper verb and the correct form of should/shouldn’t: move, use, take, catch, make, trust, yell,
1 You ***** dogs. They always know who to stay away from.
2 If you hear weird noises in the night, you simply ***** weirder noises to confirm your domination.
3 If you find a toilet in your dream, you ***** it.
4 You ***** at cats, lean in close and whisper, it’s much scarier.
5 If you are not happy where you are, you *****. You are not a tree.
6 If you drop a cactus, you ***** it.
7 You ***** decisions without eating first.
TO BE SUPPOSED TO
We can use be supposed to + infinitive instead of should/ought to to talk about an obligation to do something. It is commonly used in spoken English to express a less strong obligation which is frequently ignored: Kit is supposed to be with Luna all the time.
We can use be not supposed to’ to express prohibition:
He is not supposed to run away again.
TO BE TO
To be to is a modal expression, whose meanings are close to those of modal verbs and expressions denoting obligation: must, to have to, should, ought to.
to be to is used in the Present and Past Simple Tense.
To be to expresses:
1. Obligation or necessity arising out of an arrangement, an agreement or plan.
Luna is to come back home by midnight.
to be to in the Past Simple + Perfect Infinitive shows that the action had been arranged but did not happen. (was/were to have done)
Kit was to have stayed in Luna’s bag all the time.
to be to in the Past Simple + Simple Infinitive does not show whether the action was or was not carried out and, on the other hand, it is the only way to show a fulfilled action. (was/were to do)
Chilly was to arrange the trip.
2. Strict orders, formal commands or formal instructions.
3. A strict prohibition. May not, can’t, are not to, must not – are arranged in increasing order of severity, «must’ being an absolute prohibition: Kit is not to leave the bag until he is allowed to do it.
EXERCISE 5
Luna’s scolding Kit. Complete her sentences using the correct form of the verb in brackets with to be to and to be supposed to:
1 You ***** /obey/ me.
2 You ***** /stay/ in the bag as I had told you before the trip.
3 You ***** /let/ me know about all your intentions.
4 You ***** /tell/ me that you were going to leave the bag.
5 You ***** /have/ any secrets from me.
6 You ***** /share/ all your ideas with me instead of doing everything on your own
7 You ***** /be/ always with me so as not to make me worry big.
EXERCISE 6
Fill the gaps in the story with missing words:
Having ***** Kit, the dogs were able to resume looking ***** Kudjo. The friends had to hurry because it was getting ***** and they were supposed to come back home before nightfall. Feeling guilty and miserable, Kit kept ***** in Luna’s backpack. If he ***** run away, the dogs wouldn’t ***** wasted so much time. If the dogs hadn’t ***** so much time, they would have already ***** Kudjo. If they had found Kudjo, everybody would be ***** and cheerful. He must do something to ***** the situation. He ***** find Kudjo. If he does it, everybody will ***** him. But he can’t do it while sitting in the ***** and he isn’t allowed to get out of it. It’s totally out of the question. Suddenly it dawned on him that he ***** be able to get away in the backpack. Luna forbade him to leave her *****, but she didn’t forbid her bag to *****. What a smart kitten!
EXERCISE 7
Find and correct 7 mistakes in the sentences:
