✅ Lesson 4.2: Have to / Must / Should — Obligation & Advice

Rules, Obligations & Advice

Every day you meet three kinds of "shoulds and musts":

• Obligations — things you have to do because of a rule ("I have to wear a uniform").
• Prohibitions — things you're not allowed to do ("You mustn't smoke here").
• Advice — good ideas, but your choice ("You should see a doctor").

English has a few words for these situations: have to, must, and should. When you can use them, you can explain how your job works, warn a friend, and give kind advice. Let's learn them one by one. 🛠️

Have to / Has to

Use have to + base verb to talk about an obligation — usually a rule that comes from outside you (your boss, the law, your school say so). For he / she / it, use has to instead.

Questions and negatives use the helper do / does — just like normal present-simple verbs:

Don't Have To ≠ Mustn't

This is the most important idea in the whole lesson, so read it twice. Don't have to means it is NOT necessary — you have a choice. It does not mean "don't do it."

A simple way to remember: don't have to = free choice, mustn't = red light 🔴.

American English note: people rarely say mustn't. They usually say must not or can't: "You can't smoke here." The meaning is the same — it is not allowed.

Must / Mustn't

Use must + base verb for a strong obligation — something very important. Use mustn't (must not) for a prohibition — something you are not allowed to do. Good news: must is the same for every person — no -s, and no do/does.

graph LR
    A["must"] --> B["strong rule: DO it"]
    C["mustn't"] --> D["prohibition: DON'T do it"]
                

Should / Shouldn't (Advice)

Use should + base verb to give advice — to say something is a good idea. Use shouldn't (should not) to say something is a bad idea. Like must, should is the same for every person and takes no do/does.

To ask for advice, put should at the front:

Here is advice in a natural conversation. A starts a new job tomorrow, and B gives advice:

Putting It All Together

Here is the whole lesson in one table. Keep it near you — it answers "which word do I need?"

🔊 Hear It & Repeat — Model Sentences

Listen to each model sentence, then say it back. Use the 🎧 Audio control (bottom-right) to pick a UK or US voice and make the speed slower. These sentences use have to, must, and should for rules and advice.

Practice & Project

Tips & Common Mistakes

✅ Do's

• Use has to for he / she / it — the -s goes on has, not on the main verb.
• Use do / does for questions and negatives with have to: "Do you have to…?", "She doesn't have to…".
• Keep don't have to (your choice) and mustn't (not allowed) clearly apart.
• Use should for friendly advice; add maybe or I think to make it softer.

❌ Common Mistakes

📓 Learning Journal

📝 Lesson Summary

🎉 What You've Accomplished

You can now do something very useful in English: explain how the world around you works. You can give a rule, warn about what is not allowed, tell someone what is their choice, and give kind, useful advice. These are the words of bosses, guidebooks, doctors, and good friends — and now they are yours. 🎉

❓ Common Questions at This Stage

🔭 Looking Ahead

You have now learned a lot in Module 4: sharing life experiences with the present perfect, and talking about rules and advice. Next comes the fun part — using it all together. In Lesson 4.3, you'll bring together your past tense, present perfect, and these advice words in a Review Project: telling a full travel story.

✅ Before the Next Lesson

• Say three rules from your job or school using have to / must / mustn't.
• Give two pieces of advice to a friend using should / shouldn't.
• Write your Learning Journal entry for this lesson.