The synthetic grammar of a sentence is its internal functional structure, conventionally expressed in terms of the classes of subject, verb, object, complement and adverbial. My own ’umble feeling is that three-fifths of the conventional explanation of the internal functional structures of English sentences is a mess and, so, I hope you will forgive me if what I say about the current conventions in this area comes over as a bit lacklustre, but I am struggling to put much confidence or energy into explaining the conventions here, given their faults and limitations in my view.
Let’s look at two sentences in terms of their conventionally described functional structure:
The trainsubject pushedverb the passenger carriageobject up the hilladverbial.
The driversubject wasverb excited by the speedcomplement, with the wind rushing through her hairadverbial.
Let’s look at the details on each class of function: subject, verb etc. Let’s focus first on subjects.
The subject is one of the two main components of a sentence; the other component is the predicate, which is the rest of the sentence that says something about the subject, thus:
The trainsubject pushed the passenger carriage up the hillpredicate.
The subject can be the doer of an action, with an action verb (e.g. talked, asked), or the ‘enactor’ of a state (e.g. with knew, was):
Marysubject talked to one of the passengers on the train. Hesubject asked her the time. Shesubject knew the time from her mobile. Shesubject was happy to meet him.
With present-tense verbs, the subject determines the form of the verb, in that when the subject is third-person singular (he, she or it or a singular noun [Mary]or a singular noun phrase [his friend]), the verb form often adds an s or an es. Compare:
1st person singular: I like ice-cream; 2nd person singular: You like ice-cream; 3rd person singular: He/Mark/She/Mary/My boss/His friend likes ice-cream.
An issue with there
Because, apart from with imperatives, English insists on a sentence having a subject, we sometimes use so-called ‘dummy’ or ‘empty’ subjects, such as it or there, which have no semantic value in themselves:
It is snowing. OR There are some people at the door.
It has been suggested that, when the adverb there is used as a subject, the agreement rule, discussed directly above, between the subject and present tense verb can sometimes appear to be being flouted; if the rule is not being flouted, then that would suggest that there may not be the subject and that the form after the verb (e.g. a problem/some problems) is the real subject:
There is a problem. There are some problems.
Surely, it is stated, if there really is the subject, we should say there is some problems as there must be third-person singular and must demand the third-person singular form of the present tense of be (i.e. is). But, there is a false logic here, in that there could be being used as a plural subject form in response to the plural form of what comes after the verb are, just as happens with this (though the plurality of this [in the form these] is formally marked):
This is an issue. These are some issues.
And in fact, there is support for the idea that there can be used as a plural; when there is used just as an adverb, it can be plural in its reference, though it does not, of course, show this in its form:
I saw them together in a café and on the beach. I saw them there. (Here, there describes two ‘there’s [in the café and on the beach].)
Subjects and sentence position
It is sometimes stated that a defining characteristic of subjects is that they come before the main verb in a sentence. Compare:
Mary saw Mark. (Mary is the subject [the doer of the action].)
Mark saw Mary. (Mark is the subject [the doer of the action].)
But, others would say with more justification that position is the marker of a subject, it is not the defining characteristic of a subject. Indeed, in many question sentences, subjects occur after the verb or first verb in a sentence to show the sentence is an interrogative:
Did Mary see Mark? Has Mary seen Mark? Who did Mary phone?
Note, here, how the movement of elements of the internal functional structure of the sentence changes the function of a sentence overall, from being a statement to being a question.
Also, in older forms of English, such as in Shakespeare’s plays, where there was in the language at the time more use of inflections of the verb, word order was much more flexible than now. Even though, having said that, people sometimes use old-fashioned ways of saying things to me with very flexible word order. They know my liking for saying things in a relatively obsolete/antiquated way, methinks! A friend, for example, texted me recently saying that he had texted a mutual friend asking her if she wanted a lift from Oxford and texted me back to say he had received no reply from her to his text, by texting these words to me:
Answer came there none. (= There came no answer. OR There was no answer.)
I understood him well, even though he was flouting contemporary English word-order ‘rules’, because I knew, by other means than word position, that there was the subject of his sentence. (In case you’re wondering, I would say that answer here is part of the complement, but we’ll come on to that topic soon.)