Summary of English Modals: Can and Have To

## Introduction This unit explains the use of **can** and **have to** in English, two fundamental expressions for talking about possibilities, abilities, and obligations. You will learn forms, pronunciation, how to form questions, and how to give reasons when declining invitations. > **Definition:** *can* is used to express possibility or ability. *have to* / *has to* are used to express obligation or necessity. ## 1. Quick Summary - **Can**: possibility or ability. Form: can + base form of the verb. - **Have to / Has to**: obligation. Form: have/has to + base form of the verb. ## 2. Structure and Usage ### 2.1 Can (Possibility and Ability) - Basic form: **can + base verb**. - Examples: - We can stay out late tonight. - I can't play golf. - We can speak English. > **Definition:** *Can* indicates that something is possible or that someone has the ability to do it. ### 2.2 Have to / Has to (Obligation) - Basic form: **have to / has to + base verb**. - Examples: - I have to work late tonight. - She has to meet her cousin at the airport at 3:00. - I don't have to work late tonight. > **Definition:** *Have to* expresses an obligation or external necessity. ### 2.3 Negation and Short Answers - Can negative: **can't** or **cannot**. Example: I can't call you tomorrow. - Have to negative: **do not have to / doesn't have to** to indicate there is no obligation. - Short answers: - Can you go running tomorrow? — Yes, I can. / No, I can't. - Do they have to work tomorrow? — Yes, they do. / No, they don't. ### 2.4 Declining an Invitation - To give a reason when declining: “Sorry, I can't. I have to work late.” ## 3. Questions and Information - Questions with **can**: - Can you come on Friday? — Yes, I can. - Questions with **have to** (using auxiliaries): - Do they have to work tomorrow? — Yes, they do. - Does he have to go to class now? — Yes, he does. ## 4. Pronunciation (Brief Guide) - /kən/ unstressed form of can: I can call you today. (/kən/) - /kænt/ form of can't: I can't call you tomorrow. (/kænt/) - Note the difference in stress: in rapid speech, *can* may sound weak (/kən/), while *can't* is typically pronounced more strongly (/kænt/). ## 5. Comparative Table | Function | Structure | Affirmative Example | Negative Example | |---|---:|---|---| | Possibility / Ability | can + base verb | We can go running. | They can't play piano. | | Obligation / Necessity | have to / has to + base verb | I have to study. | I don't have to work tonight. | ## 6. Suggested Activities (Practice) 1. Write three questions using **can** and three using **have to**. Practice them with a partner. 2. Complete the sentences: - I have to study. - Audrey can't meet us for lunch today. She has to help her boss write a report. - Good news! I don't have to work late tonight. We can go running together at 6:00. 3. Find in a story: a sentence with *can't* to refuse, one with *have to* to give a reason, and a question with *can* for possibility. ## 7. Real-world applications - Giving excuses or reasons for not attending an event: “Sorry, I can't. I have to work.” - Offering availability to meet up: “I can meet at the park.” - Talking about work or academic obligations: “She has to submit the report by Friday.” Fun fact: The modal verb "can" does not change in the third person singular present tense (he can, she can), unlike ordinary verbs which add "-s".