English Grammar Negation, Questions, Emphasis

Negation

Negations are formed with the auxiliary verb "to do" in the right tense, then the word "not", and then the infinitive of the main verb. The order of elemenst is this:
subject - to do in the right tense - not -main verb inf - object - compliments, ex: I did not see him yesterday.
When there is an auxiliary verb in the sentence, a negation is formed only by the word "not":
Subject - auxiliary - not - main verb - object - compliments, ex: I have not seen him yesterday?
When "to be" is the main verbs, negations is formed only by "not".
Auxiliary- subject - main verb - not - object - compliments, ex: I am not stupid.
The words "do, does, did, have, has, had, can, could, will, would, must, is, are, was" are often contracted with the word "not".

do not - don't does not - doesn't did not - didn't,
have not - havn't has not - hasn't had not - hadn't
cannot - can't could not couldn't would not - wouldn't
will not - wan't would not - wouldn't
must not - mustn't
is not - isn't are not - ain't (very unformal) was not - wasn't

In formal written style these contractions is usually not use, in dayly speech nearly allways. Examples: He did not come - he didn't come. He has not washed the car. He hasn't washed the car.

Questions

Questions are formed with the auxiliary verb "to do" in the right tense, then the subject, and then the infinitive of the main verb. The order of elemenst is this:
To do in the right tense - subject - main verb inf - object - compliments, ex: Did you see him yesterday?
When there is an auxiliary verb in the sentence, a question is formed only by changing the word order:
Auxiliary- subject - main verb - object - compliments, ex: Have you seen him yesterday?
When "to be" is the main verbs, the question is formed only by changing the word order:
To be in the right tense - subject - compliments, ex: Were you there yesterday?

Emphasis
You can stress that something really happened by using "to do" in the right tense, and then the infinitive of the main verb. The order of elements is this:
Subject - To do in the right tense - main verb inf - object - compliments, ex: I really did see him.