Have to, must and should for obligation and advice

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


As you watch the video, look at the examples of have to, must and should. They are in red in the subtitles. Then read the conversation below to learn more. Finally, do the grammar exercises to check you understand, and can use, have to, must and should correctly.


Oliver: Amy! Hi! What are you doing here?
Amy: It's my new Saturday job. Hi, Alfie.
Oliver: Really?
Alfie: Hi.
Amy: Yes. I want to study veterinary science at university and my parents suggested I should get some experience of working with animals.
Oliver: And do you like it?
Amy: It's my first day ... Anyway. What can I do for you?
Oliver: Well, I've got some money and I've decided I'd quite like a pet. Daisy and Mum like the idea, but Mum says I mustn't get a spider, a scorpion or a snake.
Amy: That's understandable. 
Alfie: Let's see the dogs. Oh yeah! Look at these, mate! Puppies! What's that white one?
Amy: That's a Dalmatian.
Alfie: But they've got black spots, haven't they?
Amy: Not when they're puppies, no. You have to wait until they're bigger. Then the spots appear.
Alfie: Ah, I never knew that. Dalmatians are quite big, aren't they?
Amy: Yes, they are. You should really have a garden.
Oliver: Well, we've got one ...
Amy: And you have to take them out for a walk twice a day. Well, you don't have to go twice, but you must go at least once. Every day. Rain, snow, sun ... every day. And you mustn't forget to take two or three small plastic bags when you go out.
Oliver: Plastic bags?
Amy: Well, when your dog … you shouldn't leave it on the street. You should always clean it up and put it in the bin.
Oliver: Hmm.  And a smaller dog? Should I get one of these?
Amy: They're Yorkshire terriers. They're very small ...
Alfie: ... and noisy! You'd better get something a bit quieter, Ollie. Think of your neighbours!
Oliver: How about that one?
Amy: As an adult, Old English Sheepdogs are extremely large – like that one. And you've got to look after their hair regularly. You should brush them as often as possible, and get their hair cut.
Oliver: Hmm. What about a cat?
Alfie: We used to have a cat. She was a bit unfriendly. She used to scratch the sofa – and our legs – and she stole food if you left it for a moment. You've got to be careful with a cat – some are nice, but some are ... well ...
Oliver: Oh, ff. A turtle? They're small and quiet and they don't have hair ...
Amy: They grow. And then you have to buy a bigger tank. You'd better buy a thermostat and a filter if you want a turtle. And you mustn't forget to change the water; they don't smell great ...
Oliver: What about a hamster?...

Sophie: I don't know what I should do. I mean, I don't want you to feel uncomfortable ...
Daisy: I don't mind! And if you like him ... why not? He has to decide if he wants to go out with the mother of a student, though.  But he seems nice. Maybe you should go for a coffee or lunch and see how you feel? If you don't like him, you don't have to see him again.
Sophie: I shouldn't be asking you about this sort of thing! Oh, but I feel like a teenager. Why do these things have to be so complicated?
Daisy: It's not complicated, Mum! You mustn't forget, he's the one who suggested going for a drink, so he obviously likes you – and you obviously like him! What's complicated?
Sophie: I'm in New Zealand! I'm about to go and fly over volcanoes ... it's not easy to combine my kind of life with ... well, with a romance!!
Daisy: You'll be home next week, and maybe you should take some time off travelling. Spend some time with us. And with him. And I'll be leaving school in a year ... so ... go on, Mum. Life's too short! You should phone him!
Sophie: Well, I'll think about it. I'd better go – I mustn't miss the helicopter! Is Oliver there?
Daisy: No, he's out buying that pet ... ah no, here he is. Ollie, it's Mum.
Oliver: Hi, Mum!
Sophie: Did you get anything?
Oliver: Yes I did! And his name's Hannibal.

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.



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? 

Average: 4.1 (21 votes)
Personal online tutoring
EnglishScore Tutors is the British Council’s one-to-one tutoring platform for 13- to 17-year-olds.


Submitted by waytxx_x on Sun, 04/14/2024 - 14:19

I have five cats. My family can afford it, because our house is located in the countryside, so pets spend a lot of time on the yard, or walking on the street. In fact, they always want to eat, they even compose some symphonies of their synchronous meowing. I am sure that these cute kitties will eat me, if I forget to feed them someday. Of course, it's disadvantage. What about positive side. In winter I don't need a blanket as my cats loves laying on me in my bed. They are not concern about my personal opinion. And, when I pet the cat, it help me to reduse stress.

Submitted by Mohamed Saufwan on Fri, 01/19/2024 - 12:00

Yes, it is a cat. It gives babies. They are cute. They poop a lot and we have to clean.

Submitted by faysun on Fri, 08/12/2022 - 22:46

I haven't got a pet but I want a cat.My family don't want pet in the house.However my cousin have a cute cat,his name is Sushi,he is very fluffy and little fat.When I visit their house,Sushi usually sleeping.In the Turkey a lot of cats in the street.I feed them.They are very funny and warm blooded.

Submitted by cherry00 on Sat, 07/23/2022 - 13:35

I haven't got a pet but I'd like to have a cat. I love cats since I was 4. Cats are cute and make me smile every time I see one of them.

Submitted by Baldbanana on Mon, 07/11/2022 - 16:08

I've got a cat and a dog. They're cute, but we should feed them, clean up "waste" after them. They are fluffy, so we have to comb them and collect fur. They make us happy.

Submitted by Lys on Tue, 03/01/2022 - 19:26

I had a dog, her name was bony but she died a few months ago, I still miss her. I did not want to have pets again but if so I would like another chihuahua, an advantage is that they are small so I should not pick big ¿ploppies? but I have to bathe her a little more often. Also, I don't have to spend a lotof money on food because they eat very little.

Submitted by jaqueline85y on Tue, 03/01/2022 - 19:13

I have a dog, his name is Terry and he is very special to me, he is a Scottish terrier. The advantages of having a dog is that you have more contact with nature for the walks and make friends with other people who also have dogs. I honestly don't see any disadvantage to having a dog if you train it it can be very polite and quiet.
Profile picture for user FlowerQueen

Submitted by FlowerQueen on Sun, 07/25/2021 - 14:56

I haven‘t got a pet. But I want a dog, a Golden Retriever or a Chihuahua. The advantages of a Golden Retriever are that they are good for families and children. The disadvantages of a Golden Retriever are that they are really big and expensive! The advantages of a Chihuahua are that they are small, so you don‘t need so much place. The disadvantages of a Chihuahua are that some of them have a lot of hair… But maybe, I want to buy a cat. I want the kind „Birma“. They look like Siam cats. But my father doesn‘t like animals, so I can‘t have one.

Submitted by liz15 on Fri, 06/11/2021 - 20:18

when I was a litle child I had birds and they wasn't very friendly they was very rude, you can look after birds easily, they don't use a lot space, the food is cheap, you have to clean their cage every day, you must have got more than one birds because they enjoy staying with other birds, you should give them fruit like banana or Guayaba, now I have got a dog, his name is Rocky, He isn't very frendly, I have to take them out for a walk three times in a day, I must give him very good food because He is old, then it is a litle more expensive that others one, ocasionally He is nice and give me love and that is terrific.

Submitted by Arivelde on Mon, 03/15/2021 - 19:56

Yes, I do! I live in a small farm so I can have more pets than usual people. I have quite a few dogs, among them two half Pit Bulls and five Akitas Inu, some birds, a tortoise, cats... The disadvantages of having that much animals is the amount of food that they daily consume, but the advantage of it... each one of them brings it in their own ways. The cats help prevent rodent proliferation, the dogs protect us from unfriendly Intruders. The tortoise and the birds are just cute, they can help you if you are having a bad day.

Submitted by hermione123 on Sun, 04/11/2021 - 12:32

Dear Arivelde, It must be a lot of fun to live in a farm. I guess you have a big yard so you can run and play on it. I live in a small town near one of the biggest town in my country. And we don't have a big yard. But we have a small garden. I've lived in a house with no garden at all. So this garden we have now is pretty good. Because our town is kinda busy, we go to a village near a field and a lake. Near the field there is a railway where we can run on it ( there is no train, so it's all safe ) The air is so relaxing, the sun shines so bright but it feels warm there, not hot. I love watching birds, grasshoppers, butterflies and other animals and insects that live in the field. And having those pets sounds cool! You can play with them if you're bored. I don't have any pets, if i'm bored all i have is books. Best wishes ;) Hermione123

In reply to by Arivelde

Profile picture for user Cfvdv

Submitted by Cfvdv on Wed, 03/10/2021 - 16:54

Yes, I have got some dogs, but my brothers take more care of them than myself... the advantage is that they are nice and fun, but the disadvantages are because they need a lot of care and we must take them for a walk every day.

Submitted by 11mo on Thu, 11/05/2020 - 13:00

yes i have got two parrots . They are so cute.they can talk to me.

Submitted by 11mo on Mon, 11/02/2020 - 10:09

I have got two parrots. I love them so much. They can talk with me.

Submitted by Line_Sun on Sat, 10/24/2020 - 01:30

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.

Submitted by Luna on Thu, 08/13/2020 - 08:46

No, l don't have a pet but l want a puppy but it cute
Profile picture for user zagrybast

Submitted by zagrybast on Thu, 08/06/2020 - 11:59

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

Submitted by Chisaki on Fri, 06/12/2020 - 16:00

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

Submitted by Kolk on Mon, 05/25/2020 - 15:34

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.

Submitted by TR790 on Fri, 05/22/2020 - 11:51

Well, I'm not really interested in pets 'cause I don't like them.

Submitted by Alessia01 on Tue, 04/28/2020 - 07:53

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.

Submitted by cammmiloe on Fri, 04/17/2020 - 19:40

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.

Submitted by Jessica25 on Thu, 04/02/2020 - 01:09

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.

Submitted by beasam0109 on Thu, 03/26/2020 - 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

Submitted by FedericoB8 on Wed, 03/25/2020 - 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.

Submitted by bubak on Tue, 03/24/2020 - 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.

Submitted by marchese on Mon, 03/23/2020 - 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.

Submitted by bubak on Sun, 03/22/2020 - 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.

Submitted by Micheleanto on Fri, 03/20/2020 - 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.

Submitted by BttChiara on Fri, 03/20/2020 - 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...

Submitted by asiasantin on Fri, 03/20/2020 - 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

Submitted by gattifederica on Fri, 03/20/2020 - 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.

Submitted by rrfalletto on Fri, 03/20/2020 - 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.

Submitted by Carolina000 on Fri, 03/20/2020 - 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.

Submitted by JasmineD03 on Fri, 03/20/2020 - 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.

Submitted by Desy on Fri, 03/20/2020 - 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.

Submitted by Ely on Thu, 03/19/2020 - 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.

Submitted by maribel on Thu, 03/19/2020 - 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.

Submitted by giorgia_marchetti on Fri, 03/20/2020 - 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.

In reply to by maribel

Submitted by _auro_ on Fri, 03/20/2020 - 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

In reply to by maribel

Profile picture for user empty

Submitted by empty on Thu, 06/20/2019 - 14:40

Yes, I've got a pet . a super cute hamster !
Profile picture for user Youjiro

Submitted by Youjiro on Thu, 01/31/2019 - 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.

Submitted by lexgonmon on Thu, 01/24/2019 - 15:56

I have a pet rabbit :)

Submitted by Pippatwo on Thu, 06/14/2018 - 14:18

I've got a cat and some fish. One good thing is that the cat loves to watch the fish for fun. A con is that it's a lot of work to clean up after them.
English courses near you