M O D A L V E R B S
Modal verbs are a very special kind of verbs. These verbs are very similar to auxiliaries in that they occupy the same position in the sentence and they help in the construction of interrogative and negative sentences, but they are different in that they have a meaning.
Example:
(Auxiliary)
Do you swim? In Spanish it would be: Nadas?

(Modals)
Can you swim? Puedes nadar?
Will you swim? Nadarás?
Should you swim? Deberías nadar?

They have only one form, although in some cases would is considered the past of will and should the past of shall, etc.
What makes modal verbs difficult is that they have a different meaning in different contexts.
Example:
I could swim when I was six. = I had the capacity or ability to swim at
the age of six. (Past ability or capacity)
Could you open the window? = A request in the present.
I’m not sure but he could come tomorrow. = probability in the future

The following is a list of modals and the ways they are used:

CAN
1. - Present ability = be able to

- I can swim well = I am able to swim well
- Joyce can speak several languages = Joyce is able to..

2. - Permission

- Can I use your phone?
- Can I leave early today?

3. - Request

- Can you help me?
- Can you do something for me?

4. - If Clauses (1st. Case)

- He can go if he wants
- I'll help you if I can

5. - Present and future probability.

- Don't plant this tree near your house because this species can reach a height of 100 feet
- She can call you tonight

COULD

1. - Past ability = be able to (podía)

- I could stand on my head when I was younger = I was able to stand on my head when I was younger.
- They could go to the beach when they lived there = they were able to go to the beach when they lived there.

2. - Permission (podría)

- Could I talk to you?
- Could I see you later?

3. - Request (podría)

- Could you give me a hand?
- Could you do me a favor?

4. - If Clauses (2nd Case)

- I could do it if I had time.
- He would go if he could.

5. - Past opportunity (could+have+past participle)

- She could have won the race, but she didn't want to take part.

6. - If Clauses (3Rd. Case)

- I could have bought it if I had gotten the money.
BE ABLE TO replaces CAN and COULD when these can't be used.

1. - After prepositions.

- I'll be glad to be able to help you (poder).

2. - Ability in the present perfect.

- He has been able to get a good job (ha podido).

3. - Future ability.

- We will be able to swim well soon (podremos).

4. - Past fulfillment.

- They were able to escape from prison (pudieron).


WILL

1. - Future promise

- I will help you. Don't worry.

- My son will pick you up

2. - Future determination

- I will pass this course

- We will get the scholarship

3. - If clauses (1st. case)

- She will go out if her father lends her his car.

4. - Request

- Will you lend me some money?

5. - Negative / refusal in the present.

-My car won't start.

-This key won't turn.
NOTE:
6. - Simple future (only with going to) (Certainty)

- We are going to have a test next week.

WOULD
1. - Future when said in the past. (Reported speech)
-"I will come next week"......He said he would come next week

2. - Request
- Would you close the door?
3. - If clauses (2nd. case)
- I would quit this job if I had enough money.

4. - If clauses (3rd. case)
-They would have done it if they had wanted to.

5. - Negative / refusal in the past.
- I asked my brother to lend me some money, but he wouldn't.
- They tried to talk to her, but she wouldn’t listen.

MAY - MIGHT

1. - Present and future possibility
-He may (might) call you tonight

2. - Past possibility
- She may (might) have gone out last night.

3. - Permission
- May I go to the bathroom?
- May I ask you something?

SHALL
It is used for first person questions. It is not translated
1. - Offer.
- shall I help you? (Te ayudo?)
Yes, please (do). Or No, thank you.
- What time shall I call you?
Call me at two. (Wh-questions are answered with imperatives)

2. - Suggestions or invitations.
- Shall we go out tonight?
Yes, let's do / no, let's not.

- When shall we visit her?
Let’s visit her tomorrow.

SHOULD
1.-Unfulfilled obligation in the present or future = ought to
- I should do my homework tonight, but I'll go out instead.
- I ought to do my homework tonight, but I'll go out instead.

- You should be doing your homework.
- You ought to be doing your homework.

2. - Advisability = ought to.

- You look sick. You should see the doctor.
- You look sick. You ought to see the doctor

- Your grades aren't good. You should study more.
- Your grades aren't good. You ought to study more.

3. - Offer (same as shall) (It's not translated)

- Should I close the door? (Cierro la puerta?)
- Yes, please (do)/ No, thank you.

- Where should I put the boxes? (Donde pongo las cajas?)
- Put them on the floor.

4. - Suggestions or invitations (same as shall).

- Should we watch TV? (Vemos TV?)
- Yes, let's do/No, let's not.

5. - Unfulfilled obligation in the past (ought to+have+past participle).

- I should (ought to) have studied last night, but I went out instead.
- He should (ought to) have come earlier

MUST

1.-Obligation = have to (necessity)
- He must do his homework = He has to do his homework
- They must go home now = They have to go home now.

2. - Present deduction.
- She doesn't look so young. She must be around 60.
- He is wearing a white uniform. He must be a doctor.

3. - Past deduction. (Must+have+past participle)
- She arrived at the office late. She must have gotten up late.
- He looks happy. He must have won the game.

WOULD RATHER

1. - Preference
- I'd rather stay at home than go out.
- We'd rather not watch TV.

HAD BETTER

1. - Advisability.
- You'd better go to Hawaii on your next vacation.
- You'd better not make any more mistakes.

WOULD LIKE

1. - Desire (Can be followed by an infinitive or noun).
- I'd like to smoke
- We'd like some ice cream.

MSR/mbs