These notes cover pages 26-58 of Quirk & Greenbaum's A Concise Grammar of Contemporary English (Philadelphia: HBJ, 1973).
"Sometimes I think that the surest sign that intellegent life exists elsewhere in the universe is that none of it has tried to contact us."
--- Calvin & Hobbes
Note that lexical verbs constitute an open system and auxiliaries constitute a closed system. (See 2.14 if you've forgotten the difference between open and closed. Generally, you can distinguish between open and closed systems by the primary duty of the members of each class. Members of an open class (nouns, adjectives, lexical verbs, and many adverbs) mostly provide semantic material or "content," whereas members of a closed system (pro-forms, prepositions, auxiliary verbs, articles) provide syntactic information.
A verb may occur in as many as five different forms. In fact, one test for a verb is whether it takes at least two of these five forms. Study the chart on page 27
Regular lexical verbs employ all five forms. If you now the base, you can predict the other forms, and -- indeed -- with any regular form, you can predict the base. Note that this section is really about spelling rules, and you should consult it if you're creating units on spelling.
While regular lexical verbs are clearly an open system (if you coin a verb, you'll almost certainly make it a regular lexical verb), the irregular lexical verbs are pretty much a closed system. They share with regular lexical verbs, however, the primary duty of providing semantic material rather than syntactical information, so we classify them as lexical verbs. Historically, English (or proto-Germanic, the ancestor of English) had two verb systems which historical linguists call "weak" and "strong" (regular and irregular, respectively). The strong verb system was categorized into seven sub-classes, and the verbs in the little jingle which follows are (in their Old English forms) typical of the verbs in each of the sub-classes:
The cat will bite [I.] the bird that will not fly [II.]
And spring [III.] on the cat when he comes [IV.] by;
He gives [V.] no quarter and takes [VI.] no guff,
And holds [VII.] him a fool who falls [VII.] for such stuff.
One of the major difficulties you will encounter in teaching English grammar will have to do with the irregular lexical verbs. We can tell from comparing how they work in different Germanic languages that they were always a bit fluid in their categorization. Quirk and Greenbaum do an admirable job of placing our modern verbs into a seven-part system, and they draw on much historical data to do it, but -- again -- the sub-classes do not exactly correspond to the historical classes, because they are still very fluid. Currently, we hear much shifting of -ed(1) with -ed(2), where both forms are irregular: drink, drunk, have drank; ring, rung, have rang, etc. The most important thing you can do is make students aware of the fluid nature of this situation, so that they can consciously look for the way the irregular lexical verbs are used in various registers.
It should be obvious, but it may not be: do, have, and be exist as lexical verbs as well as auxiliaries. As lexical verbs, do means "to perform"; have means "to possess"; and be means "to exist." Note the list of contractions in 3.20. Contractions are a regular part of English, and are only stigmatized in formal writing, except for "ain't," which appears to have been stigmatized through the efforts of several generations of school marms.
Note the semantic force of all of the modals as variations on the ability to achieve a thing. Some dialects combine modals to create even finer variations on ability: "I might could help you" is different from "I might help you" and "I could help you." While it is clearly a dialect marker, it also represents a great complexity in the verb phrase of the user. Consider whether "can" and "could" (as well as the other paired modals) are contrasted by tense or by something else.
This is a dynamic versus a stative distinction. "He is working" uses a finite verb phrase and it is dynamic: "working" is used as a part of the verb in the progressive aspect. "I found him working" uses a non-finite verb phrase and it is stative:"working" here is a present participle, and it's adjective quality makes it stative. If you insert the deleted "to be" (I found him [to be] working), you can re-constitute the infinitive form in the non-finite verb phrase.
Note the table in 3.24. It's a major consideration of English grammar that the items always follow a clear order. I'm not aware, either, of dialects which invert these orders:
There may be gaps (e.g., he was being visited), but it's UNGRAMMATICAL to have *Hevisited have would.
The contrasts give in 3.25 include: voice, question, negation, emphasis, and imperatives.
These are the major contrasts in English. The following considerations are basic:
Not all verbs are capable of being used in a progressive construction. This is one of those places where semantics is related to grammar. If the verb is semantically dynamic (note the five classes of dynamic verbs at 3.35), then it can be progressive. If the verb belongs to one of the two stative classes, then it won't be made progressive in most variants of idiomatic English. To create a progressive out of these verbs will sound foreign, because -- in fact -- it is:
I am understanding your remarks.
The pretty box has been containing the candy.
Historical linguists love to speculate on how it is that Germanic languages have no "synthetic" future -- that is, they have no inflection to make a future the way they can make a past, although other Indo-European languages have such a future. In fact, we have at least eight ways of rendering the future through implication (and Old English had a similar inventory of futurities). If proto-Germanic were as rich in suggesting the future periphrastically (that is, using several words to do so), then the synthetic future may simply have withered away.
We usually say that there are three moods: the indicative (i.e., the attitude of indicating), the imperative (i.e., the attitude of giving commands), and the subjunctive (the attitude of supposing what is unknown or contrary to fact). The sense of the subjunctive is much more complex, however. It encompasses the following five ways of dealing with gradations of the known and the unknown:
Historically, this was an entirely different conjugation of the verb, and we can see the sort of variety it once had in the elaborate subjunctives of French or Spanish or German. Old English had an inventory of subjunctive forms as wide spread as German. Now we have some frozen forms of the subjunctive in the verb "to be" and one special form in the present, where the third person singular is not inflected with an -s. What the book calls the "mandative" subjunctive requires this verb form:
Common sense demands that he think twice.
This is, however, a very formal register for most speakers, and most of us would get around the subjunctive by saying, "It's only common sense to think twice."
There are also formulaic subjunctives (God save the Queen!, etc.), but either they are formulaic for a speaker or they are not in his/her ideolect.
Many -- but by no means all -- American speakers still have the subjunctive were for use in hypothetical instances: "If I were you, I wouldn't waste time on the subjunctive."
Other past-tense forms of "to be" may take a subjunctive sense, too: "We were catching the 8 o'clock train and it is nearly 8 o'clock." The were cannot possible mean past time here, but it is used to suggest mood appropriate to the subjunctive, that is that the train appears not to be about to arrive, so that the condition of catching it is contrary to fact.
Check the lists for an attempt to identify the gradations of meaning in the modals.
What we call modals are sometimes call "preterite-present" verbs by historical linguists. It is thought that, historically, the original past-tense form of irregular verbs came to be used as the present, and a new past-tense form was created using the inflection of the regular verb. The use of modal in setting conditions or subjunctive moods, however, make it impossible for us to think of "would" as merely the past tense of "will" etc. What may be historically a past tense has been exploited to create another modal contrast.