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Learning Objectives

2 minutes reading
✓
Use "must" for internal obligation and strong necessity
✓
Use "have to" for external obligation and rules
✓
Express prohibition with "mustn't" and "can't"
✓
Apply obligation language to policies and compliance
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Key for this lesson

Must = personal/internal obligation ("I must finish this"). Have to = external rule/obligation ("We have to follow company policy"). Mustn't = prohibition. Don't have to = not necessary.

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Grammar Explanation

4 minutes reading
Must / Have to

Obligation & Necessity

Must + base verb / Have to + base verb

Must: Personal obligation, strong feeling - "I must call the client."

Have to: External rules - "We have to wear badges."

alwaysrequiredmandatory
Mustn't / Don't have to

Prohibition vs No Necessity

Mustn't ≠ Don't have to

Mustn't: Prohibited - "You mustn't share passwords."

Don't have to: Not necessary - "You don't have to attend."

forbiddenoptionalprohibited
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Key Difference

Mustn't = DON'T DO IT (prohibition). Don't have to = you can if you want (no obligation). This is a common error!

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Context & Professional Usage

5 minutes reading

Obligation (Must / Have to)

📋Policies: "Employees must complete training."
🔒Compliance: "We have to follow GDPR regulations."
⏰Deadlines: "I have to submit the report by Friday."
👔Dress code: "Staff have to wear business attire."

Prohibition (Mustn't / Can't)

🚫Security: "You mustn't share your password."
📵Rules: "Employees can't use personal devices."
🤫Confidentiality: "You mustn't disclose client data."
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Business English Examples

6 minutes reading
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Correct Professional Usage

✓
"All employees must attend the safety briefing."

Strong internal requirement

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"We have to submit expenses within 30 days."

External company rule

✓
"You mustn't forward confidential emails."

Prohibition - not allowed

✓
"You don't have to work on weekends."

Not necessary (but you can)

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Common Business Mistakes

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"You don't have to smoke in the office."

Use: "You mustn't smoke..." (it's prohibited!)

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"I must to finish this report."

Use: "I must finish..." (no "to" after must)

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"She musts attend the meeting."

Use: "She must attend..." (no -s with modals)

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Professional Listening Exercise

6 minutes

Listen to Maria, an HR Manager at InnovateForward, explaining a new hybrid work policy to employees:

🎵Audio: New Hybrid Work Policy
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0:00 / 0:00
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Speed:

Maria: Good morning, everyone. Welcome to our quarterly All-Hands meeting. Before we get to the project updates, I need to talk about our new hybrid work policy, which starts next month. I know there are a lot of questions, so let's clarify the main points.

Maria: First, everyone has to come into the office at least two days a week. You can choose which days, but you must register them in the HR portal by the end of this month. This is a mandatory step. Your team lead is allowed to request your presence for important meetings, so please coordinate with your team.

Maria: Now, regarding office conduct. When you are here, you must wear your ID badge at all times. It's a security requirement. You mustn't use personal devices on the company's secure Wi-Fi network; you have to use the guest network for that. We are very strict about this. Also, for security, you can't let anyone into the building without a badge, not even a colleague. They have to use their own.

Maria: You are allowed to book a hot-desk for the days you come in, and you're also allowed to use collaboration spaces freely. However, you mustn't leave personal items on desks overnight. The cleaning crew needs clear spaces.

Maria: Finally, a quick note on expenses. If you work from home, you are allowed to claim up to $20 a month for internet costs. You have to submit receipts through the normal expense portal. Any questions? Please ask your direct manager first. Thank you.

Question 1: What is the minimum number of days employees must be in the office per week?

💡 Hint: Listen for "everyone has to come into the office at least two days a week."

Question 2: What is strictly forbidden according to the new policy?

💡 Hint: Listen for "You mustn't use personal devices on the company's secure Wi-Fi network."

Question 3: What are employees allowed to do regarding expenses?

💡 Hint: Listen for "you are allowed to claim up to $20 a month for internet costs."

Question 4: For security, you __________ let anyone into the building without a badge.

💡 Hint: Listen for "you can't let anyone into the building without a badge."
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Quick Comprehension Quiz

4 minutes
1

Smoking is prohibited in the office. Choose the correct form:

AYou don't have to smoke here.
BYou mustn't smoke here.
CYou shouldn't smoke here.
2

The meeting is optional. Choose the correct form:

AYou don't have to attend.
BYou mustn't attend.
CYou can't attend.
3

Company regulation: "All staff _____ complete the annual training."

Ahave to
Bdon't have to
Cmustn't
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Professional Practice Exercises

7 minutes

Exercise A: Complete with must, mustn't, have to, or don't have to

1. Everyone has to come into the office _______ least two days a week.

💡 Hint: Listen for "at least two days"

2. You mustn't use personal devices on the _______ secure Wi-Fi network.

💡 Hint: Listen for "company's secure Wi-Fi network"

3. For security, you can't let anyone into the building _______ a badge.

💡 Hint: Listen for "without a badge"

4. You must register your office days in the _______ portal by end of the month.

💡 Hint: Listen for "HR portal"
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Speaking Preparation

4 minutes
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Preparation for Class

Practice explaining rules and obligations at your workplace.

📋 Task 1: Hybrid Policy Discussion (1 min)

Explain the new hybrid work policy using must/have to/mustn't/can't.

🔓 Task 2: Your Experience (2 min)

What does/don't you have to do at your current or previous workplace? Discuss policies.

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Summary

Must/Have to: obligation
Mustn't: prohibition
Can't: not allowed
Don't have to: not necessary (optional)

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