Mustn’t vs. Don’t Have To

What you’ll learn

Distinguish an action that is prohibited from an action that is optional.

បែងចែកសកម្មភាពដែលហាមឃាត់ និងសកម្មភាពដែលមិនចាំបាច់ធ្វើ។

Meaning and use

Mustn’t means an action is not allowed or must not happen. Don’t have to means there is no necessity; the action may still be allowed. Compare You mustn’t open this box with You don’t have to open this box. The first prohibits opening it; the second leaves the choice open. With he, she, or it, use doesn’t have to. Do not interpret don’t have to as an automatic prohibition.

Mustn’t មានន័យថាហាម ឬមិនអនុញ្ញាតឱ្យធ្វើ។ Don’t have to មានន័យថាមិនចាំបាច់ធ្វើ ប៉ុន្តែអាចធ្វើបានប្រសិនបើចង់ និងបរិបទអនុញ្ញាត។ ជាមួយ he, she និង it ត្រូវប្រើ doesn’t have to។ ពាក្យទាំងពីរមិនមានន័យបដិសេធដូចគ្នាទេ។

Grammar patterns

Pattern	Example or form
Prohibited	You mustn’t open this box.
Not necessary / optional	You don’t have to open this box.
Third-person negative	She doesn’t have to come early.
Forms	mustn’t + base verb / don’t or doesn’t have to + base verb

Examples

1. You mustn’t touch that switch.

   អ្នកមិនត្រូវប៉ះកុងតាក់នោះទេ។

2. You don’t have to answer now.

   អ្នកមិនចាំបាច់ឆ្លើយឥឡូវនេះទេ។

3. She doesn’t have to work tomorrow.

   នាងមិនចាំបាច់ធ្វើការថ្ងៃស្អែកទេ។

4. We mustn’t make noise during this test.

   យើងមិនត្រូវបង្កសំឡេងរំខានក្នុងពេលប្រឡងនេះទេ។

Everyday conversation

Maly: Do I have to answer now?

Dara: No, you don’t have to. You can think first.

Maly: Can I open this box?

Dara: No. You mustn’t open it.

Common mistakes

Instead of	Use	Why
She doesn’t has to come.	She doesn’t have to come.	After doesn’t, use have, not has.
You mustn’t to touch it.	You mustn’t touch it.	A base verb follows mustn’t without to.

Practice

Try these questions before opening the answers. Write or say each answer.

សាកល្បងឆ្លើយសំណួរទាំងនេះជាមុនសិន មុននឹងបើកមើលចម្លើយ។ អ្នកអាចសរសេរ ឬនិយាយចម្លើយរបស់អ្នក។

1. Choose for a prohibition: You ___ touch that switch. (mustn’t / don’t have to)
2. Choose for an optional task: You ___ finish today; tomorrow is also fine. (mustn’t / don’t have to)
3. Complete: She doesn’t ___ to come early.
4. Does You don’t have to come mean You are not allowed to come?

Answers and explanations

Show answers / បង្ហាញចម្លើយ

1. mustn’t

   The action is not allowed.

2. don’t have to

   Finishing today is not necessary.

3. have

   Use the base form have after doesn’t.

4. No.

   It means coming is not necessary, not that it is prohibited.

Quick recap

• Mustn’t means prohibited.
• Don’t have to means not necessary, often optional.
• Use doesn’t have to with he/she/it.