Oliver and Alfie visit the local pet shop, where they are surprised to see Amy. Meanwhile, something is on Sophie's mind ... 

We use have to / must / should + infinitive to talk about obligation, things that are necessary to do, or to give advice about things that are a good idea to do.

Must and have to are both used for obligation and are often quite similar. They are both followed by the infinitive.

I must go now. / I have to go now.

Are these exactly the same?

Well, almost. We often use must for more personal opinions about what it is necessary to do, and have to for what somebody in authority has said it is necessary to do.

I must remember to get a present for Daisy.    (my opinion)   
You have to look after their hair regularly.     (dog experts say so)
Do you have to wear a tie for school?    (asking about school rules)

Which verb do people use more?

Have to is more frequent in conversation; must is used more in formal writing, for example in written notices.

Passengers must fasten their seat-belts.

Do they change in form for I, you, he, she, etc.?

Have changes in the third person singular (he/she/it has); but must doesn’t change. It’s a modal verb and modals don’t change.

I think I’ve heard have got to. Is that correct?

Yes, we use both have got to, for obligation, and had better, for advice, a lot in speaking.
 
You've got to be careful with a cat
You'd better get something a bit quieter.
I'd better go – I mustn't miss the helicopter! 
              

So they’re not used in formal writing?

No. There’s something very important about must and have to. The positive forms are very similar in meaning, but the negative forms are completely different.

You mustn’t forget ...
(don’t forget - you have no choice)
If you don't like him, you don't have to see him again.
(there is no obligation to see him again, but you have a choice)

Umm, I’m still a bit confused ...

Here's an example you can remember:
In a non-smoking area you mustn’t smoke, but in a smoking area you don’t have to smoke but you can if you want to.

Ah! Right, I mustn’t forget that.

No, you mustn’t! OK, let’s look at advice, telling people what you think is a good idea. We use should for advice, or making suggestions, and must for strong advice.

You must go for a walk with the dog at least once a day.
Maybe you should go for a coffee or lunch and see how you feel?
You shouldn't leave it on the street.

I think I’ve heard people use should in other ways, like 'he should be here in a minute' – that’s not advice, is it?

No, that’s talking about what is likely or probable. We’ll look at that use another day. We use modal verbs in different ways.

I see. So I should think about one use at a time.

Yes, exactly. You mustn’t get confused by too many uses at once.

 

Language level: 

Discussion

Have you got a pet? If you haven't got one, what kind of pet would you like? What are the advantages and disadvantages of having that particular animal? 

Comments

Line_Sun's picture
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Line_Sun 24 October, 2020 - 02:30

I’ve got a dog at home. Her name is Pepinha and for me ,she is the best dog in world. If I could I’ve got more animals but my mum doesn’t like this idea. The disadvantages are that she has a lot of desease and I have to look after because She could take a problem if she won’t take the correct medicines. In fact, my dog has a problem with their heart and she has to make a lot of exams and this kind of exams are so expansive.

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zagrybast's picture
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zagrybast 6 August, 2020 - 12:59

I have got two dogs.Their names are Leia and Gledys. They are girls. Leia is a German spitz and Gledys is a chihuahua.

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Chisaki's picture
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Chisaki 12 June, 2020 - 17:00

I have 3 goats. Their name are Holly, Jocelyn and Mei Jie. Goats are my favourite animals.

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Kolk's picture
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Kolk 25 May, 2020 - 16:34

Yes, I have one dog.
She is called Suzi.
I have to remember to feed my dog and to go for a walk with a dog.
My dog is old, she have 13 years.

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Alessia01's picture
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Alessia01 28 April, 2020 - 08:53

Hello, my name is Alessia and i have five pets. I have one dog, it's a German Spitz named Lily and it haves actually six years . She likes eating dog biscuits and it's very fluffy! I really love her as one of my brothers. I have a cat too, her name is Roni and she haves two years, she is a Calico cat, we saved her from dying of illness. My cat likes eating Cat crisps and fish. I have three fishes, one is named Nemo and the others are named Saetta and Sansa. They don't have really a preference on food, but they're really quiet! I love my pets and i want to share my love for animals with all of them. I must take the dog on a walk twice a day, and i have to clean the cat's litter. I have to feed my fishes with their fish food.

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cammmiloe's picture
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cammmiloe 17 April, 2020 - 20:40

I have a beagle dog, he has three colors, he eats a lot of, his favorite food is the cheese,he likes running with his toys in the mouth, he sleeps so much in his four beds.

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Jessica25's picture
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Jessica25 2 April, 2020 - 02:09

Yes, I have two puppies, a pug named Alan and a pincher named Danndy, the best advantage is the love they give us every day, I think there is no disadvantage.

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beasam0109's picture
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beasam0109 26 March, 2020 - 14:07

Yes, I have two dogs, Marcus and Dylan, we took them in about two years ago. they keep you company at home and they are very sweet. If I didn't have them, one of my dreams would be to adopt a dog

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FedericoB8's picture
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FedericoB8 25 March, 2020 - 18:20

Yes, I have a cat, her name is "Brioche" , every day I have to give food and clean her toilet. When we go on holiday we leave the cat to my grandmother.

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bubak's picture
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bubak 24 March, 2020 - 16:30

I have two birds. One is a girl named Lily and the other one is a boy Kiki. They are really cute and i let often them fly around my livingroom.

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marchese's picture
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marchese 23 March, 2020 - 08:47

Now no, but I had a budgie. He was so loving and cheerful, it was nice to have him at home. But he was too weak and sensitive, he needed a lot of attention. I spite of everything or take another without thinking about it.

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bubak's picture
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bubak 22 March, 2020 - 21:20

I have two birds. One is a boy and his name is Kiki, the other one is a girl named Lily. I think they're really cute, and i often let them fly around my livingroom. They like to eat lots of sunflower seeds.

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Micheleanto's picture
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Micheleanto 20 March, 2020 - 17:25

Yes, I have a cat.
For me there aren’t any disadvantages of having a cat, a cat can make you happy and relaxed, it’s funny play with him and it’s nice to pet it.

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BttChiara's picture
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BttChiara 20 March, 2020 - 15:41

Yes, I have a dog. Her name is Moka and she is a Border Collie. The advantages are that this type of dog is really friendly and lovely. I love her but the only one disadvantages is that she has to run twice a week. That is a problem because I haven’t so many time...

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asiasantin's picture
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asiasantin 20 March, 2020 - 15:33

yes, I have two dogs. They are two females and both are small. There are no disadvantages but certainly many advantages. You give yourself a lot of love, at any time of the day, even the ugliest ones

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gattifederica's picture
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gattifederica 20 March, 2020 - 14:21

I haven’t got any pets because my parents don’t want them, instead I would like to have one, more precisely, a dog. In fact my favourite animals are dogs, but I also like cats. The advantages of having a dog are the company and it can play with you. The disadvantages are: you must take it outside and sometimes you can’t take your dog on holiday. However, I hope to get one.

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rrfalletto's picture
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rrfalletto 20 March, 2020 - 13:17

yes, i have a pet, i have a very cute white rabbit. My brother has got a aquarium with a lot of fishes. But i want a dog.

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Carolina000's picture
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Carolina000 20 March, 2020 - 13:15

Yes, I have a very tender and sweet cat; he became part of my life when I was only 6 years old. Keeps me company when I feel alone and makes me smile when I feel sad. Animals have no negative sides are man’s best friend.

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JasmineD03's picture
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JasmineD03 20 March, 2020 - 11:07

Yes, I have a cat named Asia. I took it when she was only 15 days old and I've had it for almost 4 years. I love it too much and it keeps me company when my parents aren't home.
I would also like to take a golden retriever dog. The advantages of having this type of anymal are that it make you so much company and that it can give you so much love. The disadvantages are: it's very large so it takes up a lot of space in a house, it leaves a lot of hair and I don't have a garden and when I couldn't take it for a walk it should stay at home alone.

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Desy's picture
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Desy 20 March, 2020 - 10:26

I don't have pets, but I would like to have a cat. In my opinion the advantages are that the animals are cute and they keep company. The disadvantage is that my family and I love travel, and taking it with us would be very difficult.

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Ely's picture
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Ely 19 March, 2020 - 18:07

no i haven't a pet but i want a cat.
i don't have a pet because i'm never home and my home is very small.

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maribel's picture
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maribel 19 March, 2020 - 03:12

No, I don't have a pet, but I want a dog. He has the advantage that he will give me love, he will be kind and he will take care of the house. It is a disadvantage that we travel a lot.

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_auro_'s picture
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_auro_ 20 March, 2020 - 14:46

Yes, I have a pet. Her name is Margot she is a small dog.
The advantages are that he is like a friend. The disadvantages are that when we have to go somewhere we cannot always take her with us

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giorgia_marchetti's picture
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giorgia_marchetti 20 March, 2020 - 14:32

Yes, I have a dog. Her nane is Gioia and she’s 3 years old. She’s really pretty and she love play with my father’s tennis ball. I love play with her.

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Youjiro's picture
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Youjiro 31 January, 2019 - 13:02

I've got a parrot and dog in my house .Parrot is so cute and cleaver.She is so impatient because she don't get angry all of time .One good thing have a parrot is control of pet .Parrot is eazy to control under the human , but I must feed everyday to the parrot .
dog is most relevant animals all of creature I think. My dog occasionally bark to other people,but my dog is impatient. He is walking around in my house.

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