Key Difference

• “Must” is often used to express a strong obligation or necessity, usually stemming from the speaker’s own beliefs or feelings.
• “Have to” indicates an external obligation or necessity, often driven by outside factors, rules, or situations.

Structured Breakdown

1. Using “Must”

• Purpose: “Must” is used when the speaker feels a strong need for something to happen. It often conveys urgency, importance, or a rule that comes from the speaker themselves.
• Examples:
  • “You must finish your homework before going out.” (The speaker insists on it.)
  • “I must call my mother today.” (The speaker feels a personal obligation.)
• Tone and Use:
  • “Must” can sound stronger and more formal compared to “have to.”
  • Often used in rules or giving strong advice, e.g., “You must not smoke here.”

2. Using “Have To”

• Purpose: “Have to” is used to show that the obligation comes from an external source, such as laws, rules, or situations beyond the speaker’s control.
• Examples:
  • “I have to wear a uniform to work.” (This is a requirement by work policy.)
  • “We have to leave early to catch the train.” (The timing of the train dictates this obligation.)
• Tone and Use:
  • “Have to” sounds more casual in everyday speech.
  • It’s commonly used when talking about day-to-day necessities or requirements.

Comparing “Must” and “Have To” in Context

1. Personal vs. External Obligation:
   • “I must exercise more.” (A personal resolution, internal motivation.)
   • “I have to exercise because my doctor said so.” (An obligation due to an external factor.)
2. Negation Differences:
   • “Must not” (mustn’t): Indicates prohibition (not allowed). Example: “You must not park here.”
   • “Don’t have to”: Means something is not necessary (optional). Example: “You don’t have to attend the meeting if you don’t want to.”

Practice Time! 🎉

Fill in the blanks with either “must” or “have to”:

1. “You _______ speak quietly in the library.”
2. “She _______ leave early for work because of her strict boss.”
3. “I _______ remember to call my friend tonight.”
4. “They _______ follow the rules set by the school.”

✅ Answers:

1. must
2. has to
3. must
4. have to