2. WHAT ARE THEY?
Verbs that don’t follow the same
grammatical rules as others verbs and
that can also be used to express
obligation, permission, willingness, pos
sibility, etc.
3. WHICH ARE THEY?
Can Could
May Might
Shall Should
Will Would
Must Ought to
Need to Have to
Be able to
4. HOW DIFFERENT ARE
THEY?
These verbs dont use “-s” in the third person
present simple.
He cans do it. INCORRECT
He can do it. CORRECT
5. HOW DIFFERENT ARE
THEY?
They dont need “do” or “does” to form a
negative verb (Except “have to”).
I don´t will go to sleep yet. INCORRECT
I won´t go to sleep yet. CORRECT
6. HOW DIFFERENT ARE
THEY?
Some of them can´t be used in the future tense or past tense.
Instead, we use other words for similar meanings.
I will can go to the reunion. INCORRECT
I will be able to go to the reunion. CORRECT
I musted study more. INCORRECT
I had to study more. CORRECT
7. HOW DIFFERENT ARE
THEY?
They don´t use “to” in the infinitive (Except
“need to”, “have to” “ought to”…)
To may. INCORRECT
To should. INCORRECT
8. TO EXPRESS ABILITY
“Be able to”, “can” and “could”.
I can go for a ride.
He could do a banana split.
We were able to prepare a meal by ourselves.
9. TO EXPRESS PERMISSION
“Can” and “could”. “Could” is used for the past
in these cases.
I can leave the school is I wish.
They couldn´t stay at home yesterday.
10. TO EXPRESS OBLIGATION
“Must”, “need to” and “have to”
I must clean my room every weekend.
She needs to take a break, now.
You have to focus or you will fail.
11. TO EXPRESS POSSIBILITY
“May”, “might”, “could”, “should”, “ought to” and “would”.
Our project may be approved.
I ought to eat more healthy food.
This could be one of my best works.