2. Modal Verbs
Forms
•Positive: Sub. + Modal Verb +
Infinitive without to+...
•Negative: Sub. + Modal Verb+ not+
Infinitive without to +...
•Question: Modal Verb+ Sub. +
Infinitive without to + …?
•Wh- +Modal Verb + Sub. + Infinitive
without to + …?
3. MUST and HAVE TO
• You can use MUST to talk about the
present or future, but not the past.
(Internal obligations)
• We must go now.
• We must go tomorrow.
• You can use HAVE TO in all forms.
(External obligations)
• I had to go to hospital.
• Have you ever had to go to hospital?
• I might have to go to hospital.
4. MUSTN’T and DON’T HAVE
TO are completely different.
• You mustn’t do something. = It is
necessary that you do NOT do it (so,
DON’T do it)
• You must keep it a secret. You mustn’t tell
anyone.
• You don’t have to do something. = You
don’t need to do it (but you can if you
want).
• You can tell me if you want but you don’t
have to tell me.
5. MUST / MUSTN’T / NEEDN’T
• You must do something. = It is
necessary that you do it.
• You mustn’t do something. = It is
necessary that you do not do it.
• You needn’t do something. = It is
not necessary that you do it, you
don’t need to do it.
6. NEEDN’T and DON’T NEED TO
• Instead of needn’t, you can use
don’t/doesn’t need to. So you can say:
• We needn’t hurry. or
• We don’t need to hurry.
• Needn’t and don’t need to are similar to
don’t have to: We don’t have to hurry.
7. SHOULD
• You should do something. = It is a
good thing to do or the right thing to
do. You can use should to give
advice or to give an opinion.
• We often use should with I think/
• I don’t think/Do you think…?
8. SHOULDN’T
• You shouldn’t do something. = It
isn’t a good thing to do.
Example:
• You shouldn’t believe everything
you read in the newspapers.
