Obligation

An obligation is something you must do because it is necessary or important.
It can be a rule, a law, or just something that is needed in a situation.

We use have to (or has to) to talk about obligation.

Examples:

• I have to wear a uniform at school. (It’s a rule.)
• She has to do her homework before dinner. (It’s necessary.)
• We don’t have to work on Sunday. (It’s not necessary.)

Structure:

🧠 Structure: Have to / Has to

Sentence Type	Structure	Example
✅ Affirmative	Subject + have to / has to + base verb	You have to wear a helmet.
❌ Negative	Subject + don’t / doesn’t have to + base verb	He doesn’t have to go to school today.
❓ Question	Do / Does + subject + have to + base verb?	Do we have to bring our books?

Remember:

• Use has to with he / she / it.
• Use have to with I / you / we / they.

Possibility

A possibility means something that you can do.

We use can to talk about possibility, ability, or permission.

Examples:

• We can go to the beach tomorrow. (It’s possible.)
• We can visit the museum tomorrow. (It’s possible.)
• You can’t fly. (It’s impossible)
• She can’t run that fast. She’s not a superhero! (It’s impossible)

🧠 Structure: Can / Can’t

Sentence Type	Structure	Example
✅ Affirmative	Subject + can + base verb	She can travel to New York every month.
❌ Negative	Subject + can’t + base verb	People can’t fly.
❓ Question	Can + subject + base verb?	Can you buy a new computer?

🧠 Grammar Focus

Meaning	Verb	Structure	Example
Obligation (something you must do)	have to / has to	Subject + have/has to + verb	I have to do my homework.
Possibility / impossibility	can / can’t	Subject + can/can’t + verb	We can play outside. / You can’t live in the moon.

Let’s Practice

Practice 1

Practice 2

Speaking