Modals in the past form

When do we use modals?

-> To talk about someone's ability (or inability) to do something
example: "We can find your house without the street plan."
"She can't have a daughter that old!"

-> To talk about an action that is necessary (or impossible, or not necessary)
example: "You must always have your driver's license when you are driving your car."
"You needn't carry your passport around with you."

-> To talk about a situation that is possible (or impossible)
example: "Do be careful with that glass, the baby might knock it over"

A modal verb always has the same form:	There is no past form (-ed), no present participle (-ing) and no 3rd persons singular (-s).
Modal verbs come before the subject in questions:	example: "May I come to your house for tea?"
Negative forms:	Modal verbs have n't or not after them in the negative. example: "mustn't" - "needn't".

Modals in the past are :
1. Could
2. Would
3. Should
4. Shall


Could + Verb base
We can use this expression : to offer suggestion or possibilities.


Example :
Nia : I’m having trouble with math.
Rizki : Why don’t you ask Novita ?
Perhaps she could help you.


Might + Verb base
Use might to tell possibilities.
Example :
Helda : Why is Rio taking the bus to get home.
Fany : He might get a flat time.


Would + verb base
Use would for an action that was repeated regular in the past.
Example :
Yoan : What did you usually do on holidays ?
Lia : I would visit my grandparents In the village, but how not anymore.


Would + Mind + V - ing 

Use would to express polite request.
Example :
Mrs. Lady : Would you mind posting the letter ?
Nita : No, Not at all.


Should + Verb base
Example :
Noa : Liss , you should go to library now ?
Liss : Okay