A practical english grammar - Vyssaja skola 1978
Chapter 19 - The emphatic verb phrase
Sound symbols
If a speaker wants to use a verb phrase in such a way as to insist on its truth-value (in disagreement with a contrary statement or some evidence that might refute what he is saying), he uses the emphatic formula. This device shifts the stress from its normal position to the first auxiliary in cases where the verb phrase consists of two or more words; adds a form of the auxiliary do and stresses that word in cases where the verb consists of a single word (other than be); stresses the form of be itself in cases where the verb consists of a one-word form of be. This device is easy to hear in speech; in writing, it is not so easy to show, since ordinary English spelling does not indicate stress. Special type is often used.
In the sentences that follow, normal and emphatic styles are contrasted. Stress is indicated by italics:
I have been there before.
I have been there before.
They would have called us, I’m sure.
They would have called us, I’m sure.
Billy goes to that school.
Billy does go to that school.
I locked the front door.
I did lock the front door.
Mr. Grant is my son’s teacher.
Mr. Grant is my son’s teacher.
As was pointed out in connection with adverbs, the medial position with emphatic predicates is just before the first word of the verb phrase, or, in the case of one-word forms of be, before be.
They always have gone there for vacations.
He always does arrive on time.
They always are late.
Normal, unemphatic word order for the foregoing sentences would be: “They have always gone . . . ,” “He always arrives . . . and “They are always late.”