Worksheet for practicing modal verbs "should," "shouldn't," "mustn't," and "don't have to" in English grammar.

Let's solve the two sections of this grammar exercise step by step, explaining the correct usage of "should" / "shouldn't" and "mustn't" / don't have to / doesn't have to".

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🔹 Part 1: Should and Shouldn't – Giving Advice

We use:
- should → to give positive advice (recommended action)
- shouldn't → to give negative advice (not recommended)

#### ✔ Answers:

1. If you want to learn English effectively, you shouldn't speak Spanish in class. That’s a terrible idea! 😞
→ You're advised *not* to do it because it’s harmful to learning English.

2. Carmencita should go to the doctor. Her health is getting worse every day.
→ She needs medical help — it’s good advice.

3. You shouldn't tell lies to your friends. You will end up alone if you are not honest.
→ Lying is bad for relationships; so, avoid it.

4. Bob has an earache. He shouldn't listen to loud music.
→ Loud music could make his earache worse, so he must avoid it.

5. When you have a sore throat, you should drink lots of water. That’s a good idea! 🙂
→ Drinking water helps — it's a helpful recommendation.

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🔹 Part 2: Mustn't vs. Don’t Have To / Doesn’t Have To

We use:
- mustn't → prohibition (it's forbidden, dangerous, or against rules)
- don’t have to / doesn’t have to → no obligation (optional, not required)

#### ✔ Answers:

1. Gary shouldn’t interrupt his parents when they are giving him advice.
→ Wait, let's check: This is about respect, not a strict rule. But since it's about etiquette, not danger or law, we use shouldn't. However, the section says “mustn't vs. don’t have to”, so perhaps the intended answer is mustn't? Let’s reconsider.

Actually, mustn't implies a strong rule or danger. Interrupting parents isn’t usually illegal, but it’s rude. So shouldn't would be better. But since the exercise asks for mustn't or don’t have to, and mustn't is stronger, maybe it's meant to be mustn't?

✘ Wait — the instruction says: *"Complete using 'mustn't' or 'don't have to / doesn't have to'"*, so only those two options.

But interrupting parents isn’t something that’s *forbidden* (like smoking at gas stations), so mustn't is too strong.

However, in many educational contexts, mustn't is used for rules like "you mustn't talk during class".

But here, it's advice, not a rule. So actually, mustn't might be incorrect.

Let's analyze carefully:

- mustn't = prohibited (e.g., "You mustn't smoke here.")
- don’t have to = not necessary (e.g., "You don’t have to wear a hat.")

In sentence 1: "Gary _______ interrupt..." — it's a recommendation, not a rule. So neither fits perfectly.

But since the exercise forces us to pick between mustn't or don’t have to, and interrupting is not allowed, we can interpret it as a rule in a family context.

→ So: mustn't

✔ Gary mustn't interrupt his parents when they are giving him advice.

✔️ Reason: It's a behavioral rule in a respectful setting — not optional.

2. You don’t have to watch this movie with us if you don’t want to. It’s up to you!
→ There’s no obligation — it’s optional.

✔ don’t have to

3. Drake doesn’t have to buy food from the school cafeteria. He can also take his own snacks from home.
→ He has a choice. No requirement.

✔ doesn’t have to

4. You mustn't smoke at gas stations!
→ This is a dangerous activity and strictly forbidden due to fire risk.

✔ mustn't

5. Children mustn't open the door to strangers. It can be really dangerous!
→ Safety rule — it’s forbidden for safety reasons.

✔ mustn't

6. Sarah doesn’t have to wear a uniform for work. She can wear her regular clothes; it depends on her.
→ No requirement — it’s optional.

✔ doesn’t have to

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✔ Final Answers:

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#### Part 1: Should / Shouldn't

1. shouldn't
2. should
3. shouldn't
4. shouldn't
5. should

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#### Part 2: Mustn't / Don’t Have To / Doesn’t Have To

1. mustn't
2. don’t have to
3. doesn’t have to
4. mustn't
5. mustn't
6. doesn’t have to

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🔍 Summary of Key Differences:

| Expression | Meaning | Example |
|-------------------|------------------------------------------|----------------------------------|
| should | Good advice / recommended | You should eat vegetables. |
| shouldn't | Bad advice / not recommended | You shouldn't skip meals. |
| mustn't | Prohibited / dangerous / against rules | You mustn't run in the hallway. |
| don’t have to | Not necessary / optional | You don’t have to come early. |

> Note: mustn't = strong prohibition (often safety or rules)
> don’t have to = lack of obligation (choice involved)

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✔ All sentences now correctly reflect the intended meaning with proper modal verbs.