Most of the time in English Verb Structure the main verb, which tells the action of the sentence, is preceded by another verb, called an auxiliary verb. This puts the action of the main verb in the proper context. It can tell us the tense of the verb or, if it is a modal auxiliary verb it indicates permission, obligation, or possibility. Auxiliary Verbs are very important in English because they are a a very important part of English Verb Structure.
So in positive statements all auxiliaries come directly before the main verb.
The most common English Verb Structure that is used the most is the Positive form. Which is like this;
SUBJECT-AUXILIARY-VERB
So the important this to remember is that in positive statements all auxiliaries come directly before the main verb, the exception to this is the Simple Tenses, Present Simple and Past Simple. I these tenses you do not need to use the auxiliary verb in the positive form.
This form of english verb structure is almost exactly the same as for positive sentences, but we use the word “not” before the main verb to make it negative.
SUBJECT-AUXILIARY+NOT-VERB
We use contractions with the Auxiliary a lot with the negative structure to make things quicker and easier to say.
do not = don’t
have not = haven’t
The final form of english verb structure is the question form. The biggest difference for questions is that the auxiliary verb no longer comes directly before the main verb. It moves to be before the subject.
Like in the negative structure, there must always be an auxiliary verb. Sentences with this structure are questions and should, therefore, end with question marks.
Understanding these forms of English Verb Structure is a simple but effective way to improve you English. It is part of EVERY sentence but a lot of people make basic mistakes with it so it is worth investing some time to understanding it and look out for it as you read and listen to English.