Auxiliary verbs, as we have seen, are “helping” verbs that add structural meaning or a semantic coloring to verbs carrying the full burden of lexical meaning. All auxiliaries share the ability to be directly followed by not in negative sentences, often in contracted form (They have not gone, We shouldn’t wait), and to be reserved with the subject in questions (Have they gone? Should we wait?)
TYPES OF AUXILIARIES
There are three types of auxiliaries, each serving a different purpose.
TENSE AUXILIARIES: be, have, will/shall
The tense auxiliaries perform a structural function only. Be occurs with the -ing present participle in the progressive forms of the tenses. Have is used for the perfect tenses. Shall and will are used for the future tenses.
Be and Have are also independant verbs.
The do auxiliary is accompanied by the simple form of the verb (the infinitive without to). It is used only in simple present tense (do or does offer) and in the simple past tense (did offer). It provides an auxiliary to auxiliary-less verbs to enable them to function in the following grammatical patterns.
Do you like this website?
2. Negative statement
I don’t like your new dress.
3. Reduction- omission or substitution
Do you like my new dress? Yes, I do.
I don’t like coffee and neither my wife. (or my wife doesn’t either.)
I study more than my friend does.
He should study hard. Whenever he does, he gets good grades.
a. A positive contrasting with a negative (often introduced by but)
My teacher thinks I didn’t study for my test, but I did study.
b. With negative expression
The letter we were expecting never did arrive.
c. With concessive type of contrast
Although I have little time for entertainment, I do go to theater once in a while.
He does have money, but it’s all tied up in property.
d. As a positive resolution after some doubt
We’re very pleased that she does not intend to come.
e. With emphatic adverbs: definitely, positively, certainly.
Do you remember how beautiful she was? I certainly do remember.
5. Entreaty (especially British usage)
Do come to the party tonight.
In older usage, do often appeared in positive statements, in variation with the simple present form.
Thus conscience does make cowards of us all. (Shakespeare)