DEFINITION:
Verbs are different. They have a number of special features. These verbs can express: duty, necessity, and prohibition, absence of necessity, probability, possibility, and ability.
CHARACTERISTICS:
Verbs are incomplete. They have no participle or infinitive, and others need to complete conjugation verbs: CAN is completed BE ABLE TO periphrasis, with MUST HAVE TO, etc.
No carry- 3rd person singular present simple, except TO HAVE (HAS TO)
All are followed by another verb in the infinitive without TO, except Ought to, HAVE TO and NEED TO.
As auxiliary verb do not need, build the interrogative reversing the order of subject and verb, and adding negative NOT.CANNOT
MUST
MUST verb and which can be attributed two main meanings: to indicate that we are sure of the certainty of something and to express an opinion, that is indicate that something must be done, for example:
He must have a lot of money. She must be at home. You must follow the rules. They must pay attention.
To use the modal verb MUST in a question, we must place at the beginning of the question, for example:
Must you go to school today? Must we visit your parents?
However, to build the negation with the modal verb MUST we proceed the following way.
We must not spend the money. You must not move to London.
CAN
The verb CAN. It is a term that indicates ability, ie the ability to do something or even possible, or is that something may materialize, for example:
He can build a house. They can repair the car. It is expensive but I can buy it.
You can dance better. Note that the verb CAN always accompanied by a principal verb in the infinitive and as already mentioned, in the third person singular is not added the S.
To interrogate using the modal verb CAN, we must place at the beginning of the question, for example:
Can you lend me money? Could he repair the car?
To develop the negative of CAN in present simple CAN NOT be used or contracted form CAN NOT. If we do it in the simple past can place COULD NOT or COULDN`T contraction, as illustrated below
He cannot travel to Europe. He can't travel to Europe. She could not study the lesson. She couldn't study the lesson.
HAVE TO
"Have to" is used to express certainty, necessity, and obligation. Examples:
This answer has to be correct. The soup has to be stirred continuously to prevent burning. They have to leave early.
OUGHT TO
Ought to" is used to advise or make recommendations. "Ought to" also expresses assumption or expectation as well as strong probability, often with the idea that something is deserved. "Ought not" (without "to") is used to advise against doing something, although Americans prefer the less formal forms "should not" or "had better not." Examples:
You ought to stop smoking. Jim ought to get the promotion. It is expected because he deserves it. This stock ought to increase in value. Mark ought not drink so much.
SHOULD
We continue with modal verbs and in this case SHOULD discuss. This is a modal verb used to express convenience, for example:
He should get a new job. You should study English.
They should know the truth.
The modal verb SHOULD also be used to express the probability of something happening in the future, for example:
You have saved a lot of money so you should buy a new car. She has worked the whole year so she should have holidays.
To express something that should have been done in the past but did not use the form SHOULD + HAVE + past participle of the main verb, for example:
He should have arrived earlier. We should have travelled yesterday.
The negative form of the modal verb SHOULD be constructed the following way:
I should not spend all the money. He should not drive so fast.
You can also replace their SHOULD NOT contracted form SHOULDN`T.
MAY
"May" is most commonly used to express possibility. It can also be used to give or request permission, although this usage is becoming less common.
Examples:
Cheryl may be at home, or perhaps at work. Johnny, you may leave the table when you have finished your dinner. May I use your bathroom?
WILL
"Will" is used with promises or voluntary actions that take place in the future. "Will" can also be used to make predictions about the future. For more information on using "will" and associated exercises, visit the Simple Future section of our Verb Tense Tutorial.
Examples:
I promise that I will write you every single day. I will make dinner tonight. He thinks it will rain tomorrow.
WOULD
"Would" is most commonly used to create conditional verb forms. It also serves as the past form of the modal verb "will." Additionally, "would" can indicate repetition in the past. For more information on the grammar behind the modal verb "would," visit the following tutorials: Conditional Tutorial, Future in the Past, and Would Always. Examples:
If he were an actor, he would be in adventure movies. I knew that she would be very successful in her career. When they first met, they would always have picnics on the beach.
COULD
Could" is used to express possibility or past ability as well as to make suggestions and requests. "Could" is also commonly used in conditional sentences as the conditional form of "can." Examples:
Extreme rain could cause the river to flood the city. Nancy could ski like a pro by the age of 11 You could see a movie or go out to dinner. Could I use your computer to email my boss? We could go on the trip if I didn't have to work this weekend.