Modals Verbs Ingles

Modal verbs, also called modal auxiliaries or simply modals, are a type of auxiliary verb or helping verb. English has ten modal verbs:
can |   | could |
may |   | might |
shall |   | should |
will |   | would |
must |   | ought to |
Modals express the mood a verb, such as ability, possibility, necessity, or another condition. They are used with a main verb to form a sentence or aquestion. Modals are not conjugated, have no tense, and cannot be used without a main verb.
When used with modal verbs (except ought), main verbs always remain in the infinitive without to.
In a statement the word order is subject + modal + main verb.
subject | modal | main verb |
They | can | come. |
Mike | should | walk. |
In questions, the word order changes to modal + subject + mainverb.
yes-no questions |
modal | subject | main verb |
Can | they | come? |
Should | Mike | drive? |
wh- questions |
wh- word | modal | subject | main verb |
When | can | they | come? |
How | could | he | know? |

Can
The modal can indicates possibility or ability:
Tom can help you.
Wild animals can be dangerous.
Dining out can be costly.
In questions, the modal can requestspermission to do something or to ask about possibilities:
Can I help you?
Can Mike come over for dinner?
Who can answer the next question?
When can we get back the results?

Could
Could indicates possibility or ability in the past:
I could have told you that.
It could have been a disaster.
When I was young, I could run very fast.
Could speculates about future posibilities. In thefollowing examples could and might are synonomous.
It could / might rain tonight.
That could / might be dangerous.
In yes-no questions, could speculates about present posibilities:
Could she be the murderer?
Could this be a mistake?
It can also make a request. In these examples could and can are synonomous, but could is more polite.
Could / Can you open your window?
Could / Can you help me movethis sofa?
Could indicates an option:
We could go see a movie.
I could become a doctor.
The modal could is also used to form the conditional. The conditional contains an if clause and a result clause. Could is placed in the result clause.
In these examples, could expresses hypothetical situations:
If I had time, I could play tennis with you.
We could study together, if you want to.
If itweren't raining, we could go on a picnic.
Could mentions something that didn't happen because a certain condition was not met:
If we had left sooner, we could have taken the train.
I could have passed the exam if I had studied more.
I'm glad we took umbrellas. We could have gotten soaked.

Shall and Will
The modals shall/will + main verb are used to create future tenses. These modalsindicate an intention or an action that is expected to happen in the future.
When used in statements, there is no difference in meaning between these two modals; however, shall is rarely used in American English.
I will / shall close the door for you.
Tom will / shall meet us at the train station.
They will / shall leave tomorrow at 8:00.
In wh- questions, shall and will ask about options.
Whowill / shall drive the car?
When will / shall I see you again?
How will / shall you get here?
What time will / shall we meet?
In yes-no questions, shall and will have different meanings.
Will asks a favor.
Will / Shall you turn off the TV?
Will / Shall you stop whining?
Will / Shall you go with me?
Will also asks for information or knowledge about somebody or something.
Will / Shall Tomever pay you back?
Will / Shall Mars be visited by humans within twenty years?
Will / Shall you be finished soon?
Shall asks about a preference. In these examples, shall and should are synonomous. In American English, shall is rarely used; when it is, it's only in the first person singular and plural.
Should / Shall I close the door?
Should / Shall he close the door?
Should / Shall they...