have to, should, must

1. Modals: Describing
Obligation & Advice

2. Must
it’s obligation, there is no
other choice

3. Mustn’t
it’s obligation NOT to do it

4. should
I
You
We
They
He
She
it
must / mustn’t

5. Must
We must learn more about the fight to
save rhinos.

6. have to
it’s necessary

7. don’t have to / doesn’t have to
it’s NOT necessary

8. have to
I
You
We
They
He
She
it
have to
have to
has to
have to

9. We have to protect rhinos.

10. We don’t have to use products made
from rhinoceros horn.

11. The rhino doesn’t have to worry anymore
because now he is protected.

12. should
it’s recommended, it’s
advisable, it’s a good idea

13. shouldn’t
it’s NOT a good idea / it’s
NOT recommended

14. should
I
You
We
They
He
She
it
should / shouldn’t

15. should
Everyone should do something, even if
it’s a small action.

16. shouldn’t
We shouldn’t ignore the rhino problem.

17. NOW, let’s!