Welcome to this English lesson focused on talking about obligation! If you’re learning English at a B1 level, you’re probably starting to feel more comfortable expressing yourself. Now, let’s learn how to talk about things you must do, have to do, should do, and more! Understanding obligation is super important for everyday conversations, whether you’re talking about work, studies, or just daily life. Let’s make it easy and practical!

What is Obligation in English?

Obligation is about saying what is necessary or required. It’s about expressing duties, rules, responsibilities, and things that are expected of us. We use different words and phrases in English to show different levels of obligation, from very strong to weaker suggestions. Learning to use these correctly will make your English sound more natural and precise.

Common Ways to Express Obligation

Let’s explore the most common ways to express obligation in English. We’ll look at ‘must’, ‘have to’, ‘need to’, and ‘should’.

Using “Must” for Strong, Internal Obligation

We use “must” to talk about obligations that come from ourselves, or when something is very important and necessary, often because of a rule made by the speaker. It shows a strong sense of obligation.

• Example 1: I must study for my English exam. (This is my own strong feeling of obligation because I want to pass.)
• Example 2: You must wear a seatbelt in the car. (This is a strong rule, often a law.)
• Example 3: We must remember to call Grandma on her birthday. (Important personal obligation.)

Remember, “must” often expresses a personal obligation or a rule the speaker feels strongly about.

Using “Have to” for External Obligations and Rules

“Have to” is used for obligations that come from outside of us – rules, laws, or someone else. It’s about external necessity. It’s also very common in everyday English.

• Example 1: I have to go to work tomorrow. (My job requires it; it’s an external obligation.)
• Example 2: Students have to wear a uniform at this school. (School rule – external obligation.)
• Example 3: We have to pay taxes every year. (Law – external obligation.)

Notice how “have to” usually comes from rules, laws, or someone else’s authority. It’s less about personal feeling than “must”.

Using “Need to” for Necessity

“Need to” expresses necessity or requirement. It’s similar to “have to” but can sometimes feel a little less strong. It focuses on what is necessary to achieve something or because of a situation.

• Example 1: I need to buy groceries. (It’s necessary because I want to eat.)
• Example 2: You need to practice English speaking to improve. (Necessary for progress.)
• Example 3: We need to leave now if we want to catch the train. (Necessary because of time constraints.)

“Need to” is often about what’s necessary to reach a goal or handle a situation. It’s a very useful way to talk about obligation in English.

Using “Should” for Weaker Obligation and Advice

“Should” is used for weaker obligations, recommendations, and giving advice. It’s less forceful than “must” or “have to”. Think of it as saying something is a good idea or the right thing to do, but not strictly a rule or law.

• Example 1: You should eat more vegetables. (Advice for health.)
• Example 2: They should apologize for being late. (Recommendation for good behavior.)
• Example 3: We should probably book our tickets in advance. (Suggesting a good idea.)

“Should” is perfect for giving suggestions and talking about what is generally a good or expected thing to do. It’s less about strict rules and more about what is advisable.

Negative Obligation and Lack of Obligation

Now, let’s look at how to talk about things that are not obligatory, or things you must not do.

“Mustn’t” (Must not) for Prohibition

“Mustn’t” or “must not” is used to express prohibition – things that are not allowed or are forbidden. It’s a strong negative obligation.

• Example 1: You mustn’t smoke here. (It’s forbidden – strong negative obligation.)
• Example 2: Children mustn’t play with fire. (It’s dangerous and not allowed.)
• Example 3: We must not forget our passports. (Very important not to forget.)

“Mustn’t” clearly says “do not do this!” It’s a strong way to express prohibition.

“Don’t have to” / “Doesn’t have to” for Lack of Obligation

“Don’t have to” or “doesn’t have to” means there is no obligation. It’s not necessary to do something. It’s the negative form of “have to”.

• Example 1: You don’t have to come to the meeting if you’re busy. (It’s optional, not obligatory.)
• Example 2: She doesn’t have to work on Sundays. (It’s not required by her job.)
• Example 3: We don’t have to cook dinner tonight; we can order pizza. (Not necessary to cook.)

“Don’t have to” and “doesn’t have to” clearly indicate that something is optional and not required.

“Don’t need to” / “Doesn’t need to” for Lack of Necessity

Similar to “don’t have to”, “don’t need to” or “doesn’t need to” also expresses a lack of necessity. It means something is not necessary, often because it’s already done or not required in the current situation.

• Example 1: You don’t need to water the plants; it rained yesterday. (Not necessary because of recent rain.)
• Example 2: He doesn’t need to wake up early on Saturday. (Not necessary because it’s his day off.)
• Example 3: We don’t need to buy bread; we have plenty at home. (Not necessary because we already have it.)

“Don’t need to” and “doesn’t need to” are about lack of necessity – something is not required because of the circumstances.

“Shouldn’t” (Should not) for Advice Against Something

“Shouldn’t” or “should not” is the negative form of “should”. It’s used to give advice against doing something. It means it’s not a good idea or it’s not recommended.

• Example 1: You shouldn’t eat too much sugar. (Advice for health – not recommended.)
• Example 2: They shouldn’t be late for class. (Advice for good behavior – not recommended.)
• Example 3: We shouldn’t forget to take our umbrellas; it might rain. (Advice based on a possibility – not recommended to forget.)

“Shouldn’t” is used for giving advice against something, saying it’s not a good idea or not recommended. It’s a weaker negative obligation.

Let’s Practice Talking About Obligation!

Now it’s your turn to practice! Fill in the blanks with the correct word from the box below to express obligation or lack of obligation.
Word Box: must, have to, need to, should, mustn’t, don’t have to, shouldn’t

Fill in the Blanks

1. You _______ be quiet in the library. It’s a rule.
2. I _______ go to the doctor. I feel very sick.
3. She _______ work late tonight. The project is finished.
4. We _______ eat so much junk food. It’s bad for us.
5. They _______ arrive before 8 am. It’s essential for the meeting.
6. You _______ worry so much. Everything will be alright.
7. He _______ clean his room; it’s a mess!

Transformation Exercises

Rewrite the following sentences using the word in brackets to express obligation or lack of obligation in a different way.

1. It is necessary for me to wake up early tomorrow. (have to)
2. It is a good idea to drink more water. (should)
3. It is forbidden to park here. (mustn’t)
4. It is not necessary for you to buy milk. (don’t need to)
5. It is essential that you finish your homework. (must)

Answers

Fill in the Blanks Answers:

1. You must be quiet in the library. It’s a rule.
2. I have to go to the doctor. I feel very sick.
3. She doesn’t have to work late tonight. The project is finished.
4. We shouldn’t eat so much junk food. It’s bad for us.
5. They must arrive before 8 am. It’s essential for the meeting.
6. You shouldn’t worry so much. Everything will be alright.
7. He needs to clean his room; it’s a mess!

Transformation Exercises Answers:

1. I have to wake up early tomorrow.
2. You should drink more water.
3. You mustn’t park here.
4. You don’t need to buy milk.
5. You must finish your homework.

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We hope this lesson has helped you understand how to talk about obligation in English. Keep practicing, and you’ll become more fluent and confident in your English speaking skills!