The formal structure might be presented in several ways. Some of them where described in Chapter One §§ 5-7. A sentence might be presented as a sequence of distributional classes of words. But this presentation shows only the composition of it, and does not indicate relations between the components. This presentation only partially reflects the sentence structure. Another variant is found in the IC analysis. This analysis gives some information about relationships of the elements of the sentence, but only about dependence of the elements. It means that this type of presentation also only partially reflects the sentence structure. These two types of reflecting sentence structure do not give enough information about the functional characteristics of the sentence elements. The method designed for showing as many functions as possible is known as the model of members of the sentence. This model is as old in Europe as linguistic analysis itself. It states that a sentence includes the main members, namely the subject and the predicate, and each of these may have dependent secondary members. This division of a sentence into the subject-predicate group is supported by one of the ways of formalising predicativity, and namely the disjoined one, when the personal predicativity finds its own element for its embodiment.
The other elements of the sentence should be subordinated to these two main elements and are differentiated according to the grammatical class of words they are directly connected to. All elements subordinated to a noun are called attributes. The elements depending upon the verb or the adjective belong to two classes: the elements whose headword is a noun or a noun-like element are usually named objects, and the elements being adverbs or prepositional phrases or sometimes nouns indicating time and measure are known as adverbial modifiers. This description shows that formal distinction between objects and adverbial modifiers is not possible because both of them can be nouns. Usually semantic features of these groups are taken into consideration. From that point of view, the objects are those nominal groups that name things in any way involved into the action, state or relation named by the verb. The technique used to identify involvement is putting a question to the element. If the question includes what or who(m) then the unit is an object, if not then it is an adverb. For example: John read a book — What did John read?; John looked at Jane — At whom did John look? In these sentences the elements book and Jane are objects. But if we take sentences like Two days ago John came back the question to the noun group two days ago is When did John come back? Thus the group is an adverbial modifier.
Simple as the procedure seems it rather often produces confusing results. If we take a sentence John is sitting at the table we may ask two questions Where is John sitting? and At what is John sitting? We have to choose which of the questions is showing the syntactical function of the group. To do so we may substitute the group with an adverb and if it is possible we may say, that the group is an adverbial modifier. In case it is impossible, the group should be classified as an object. But even this method does not always give unambiguous results. For example, if you apply both techniques (question and substitution) to the sentence Jane entered the room we receive the following: What did Jane enter? and Jane entered there. This conflicting evidence makes us come back to the formal features and consider that the room is an object, because it does not have a preposition and does not belong to the words naming time and measure.
These three methods of identifying the structure of the sentence cannot give absolutely non-ambiguous results and we have to use them alternatively or in combination to present the formal structure of the sentence. Yet in English we can find rather specific features that can help us to present the structure of the sentence almost unambiguously. For that we shall describe the four mentioned above members separately and each described from three points of view: composition, dependence and function.