Expressing Obligation, Prohibition, Lack of obligation

Modal verbs such as must, have to, must not, and don’t have to help us express different degrees of obligation and prohibition. Below is a comprehensive guide with many simple example sentences and emojis for each context.

1. Using “Have to” for External Obligations

“Have to” shows obligations imposed by external rules, laws, or circumstances.

Sentence Structures

Present: Subject + have to + base verb
Example: I have to wear a uniform to work. 👔
Past: Subject + had to + base verb
Example: I had to finish my homework last night. 📝
Future: Subject + will have to + base verb
Example: I will have to leave early tomorrow. 🚪

Examples

I have to wake up at 6 AM every day. ⏰
You have to wear a helmet when riding a bike. 🚴‍♀️
She has to follow the school rules. 📚
We have to pay our bills by the due date. 💵
They have to attend the meeting at 9 AM. 🏢
The team has to complete the project on time. ⌛
I had to cancel my plans due to the storm. 🌩️
He had to take an extra shift at work yesterday. 🕒
Tomorrow, you will have to present your report. 📊
We will have to reschedule the event if it rains. 🌧️
The law says you have to wear seatbelts. 🚗
Students have to submit their assignments by Friday. 📅

2. Using “Must” for Strong, Personal Obligations

“Must” expresses personal necessity, moral duty, or strong recommendations.

Sentence Structure

Subject + must + base verb
Example: I must finish my assignment before dinner. 🍽️

Examples

I must study hard for my exam. 📚
You must try to be on time. ⏱️
She must call her mother today. ☎️
He must exercise to stay fit. 🏋️‍♂️
We must respect our teachers. 👩‍🏫
They must recycle to protect the environment. ♻️
I must not forget to water the plants. 🌱
You must complete your chores before playing. 🧹
She must apologize for her mistake. 🙇‍♀️
He must wear his safety gear on site. 🦺
We must support each other during tough times. 🤝
Everyone must contribute to the team project. 💼

3. Using “Must Not” for Prohibition

“Must not” (or “mustn’t”) is used to indicate that an action is strictly forbidden.

Sentence Structure

Subject + must not + base verb
Example: You must not leave the door open. 🚪❌

Examples

You must not run in the hallways. 🏃‍♂️🚫
Children must not play near the road. 🚸
Students must not use their phones during class. 📵
You must not smoke in this area. 🚭
Employees must not share confidential information. 🔒
Drivers must not exceed the speed limit. 🚗⚠️
Visitors must not enter restricted zones. 🚷
You must not eat in the library. 📚❌
Pets must not be left unattended in the store. 🐕🚫
No one must use the equipment without training. ⚙️🚫
You must not tamper with the fire alarm. 🔥❌
Guests must not bring outside food. 🍔🚫

4. Using “Don’t Have To” for Lack of Obligation

“Don’t have to” indicates that there is no requirement or necessity to do something; it is optional.

Sentence Structure

Subject + don’t/doesn’t have to + base verb
Example: You don’t have to come if you’re busy. 🙅‍♀️

Examples

I don’t have to work on weekends. 😎
You don’t have to bring your lunch; it’s provided. 🍱
He doesn’t have to wear a uniform at his new job. 👔🚫
We don’t have to attend the meeting if it’s canceled. 📅
They don’t have to clean the house today. 🧹
She doesn’t have to come early if traffic is bad. 🚗💤
I don’t have to study tonight because the exam is next week. 📚
You don’t have to join the call if you’re busy. 📞
He doesn’t have to cook dinner; we can order in. 🍕
We don’t have to worry about the weather today. 🌤️
They don’t have to follow the dress code on casual Fridays. 👖
She doesn’t have to work late if the project is finished. 🕰️

5. Using “Had to” and “Will Have to” for Past and Future Obligations

Because “must” has no past tense, we use “had to” for past obligations and “will have to” for future obligations.

Sentence Structures

Past: Subject + had to + base verb
Example: I had to complete the report yesterday. 📝
Future: Subject + will have to + base verb
Example: She will have to leave by 8 PM. ⏰