The criteria adopted for the classification of clause functions are four: determination by the verb, position, ability to become the subject and realisations of these functions.
1. Determination by the verb
The number and type of objects and complements that can occur in a clause are determined by the verb according to its potential. We say that a certain verb predicts an object or a complement. Eat, for example, predicts an object that expresses the thing eaten. One sense of carry predicts an object that refers to the thing carried (They carried backpacks). Disappear, however, does not predict or admit an object (*He disapppeared the money). Determination is related to verb class.
Transitive verbs usually require one or more objects. They occur in type SPO (carry), type S-P-Oi-Od (send), and type S-P-O-C (find) in one of its uses.
Intransitive verbs such as disappear occur in type S-P. They do not admit an object, but certain intransitive verbs predict a complement of space or time, as will be explained shortly.
More exactly, we should talk about transitive or intransitive uses of certain verbs, as a great many verbs can be used in English both transitively and intransitively. Land is transitive in The pilot landed the plane safely, but intransitive in The plane landed. Carry is transitive in They carried backpacks, but it has an intransitive use in His voice carries well (= ‘projects’).
A locative element is required by a few transitive verbs such as put and place (Put the handkerchiefs in the drawer; Place the dish in the microwave). Without this locative element, the clause is syntactically and semantically incomplete (*Put the dish). It therefore has the status of a central clause element. A locative element is also predicted by many intransitive verbs of motion such as come, go, fly, drive, which can predict such meanings as Direction (flying south) and Goal, which marks an end-point (go to Rome). Both types will be represented here as Locative/Goal Complements subsumed under the abbreviation (Cloc). However, it is also possible to use these verbs without a locative, as in for example Are you coming? Don’t go! I’ll drive. (Drive in fact predicts an object or a locative or both, as in I’ll drive you to the station.)
From these we can see that prediction is less strong than requirement. An expression of manner is required with one sense of treat (they treated the prisoners badly) and with the intransitive verb behave (she has been behaving strangely lately). The verb last predicts an expression of extent in time (the concert lasted three hours); however, sometimes the lack of duration can be inferred as in Their love didn’t last. When predicted
or required by the verb, elements such as place or time are analysed as circumstantial Complements, the equivalent of obligatory adverbials in some grammars.
Copular verbs, a type of intransitive, require a Subject Complement. Only verbs capable of being used as copulas can be used in this way. So, for instance, be and feel as in I am cold, I feel cold can be used as copulas in English but touch cannot (*I touch cold).
Besides predicting an attribute, verbs of being such as be, remain, stay predict being in a location. Their Complements are then analysed as locative (Cloc). The following examples illustrate the parallel between attributes as Subject and Object Complements and the Locative/Goal types. Evidently there are many other verbs which function in only one of these patterns:
Attributive Locative/Goal
He stayed calm He stayed in bed
She went pale She went to work
He drives me mad He drives me to the airport
A bicycle will get you fit A bicycle will get you to work
By contrast, adjuncts are not determined by any particular type of verb. Suddenly, for instance, can be used with intransitive verbs like disappear and transitive verbs like carry. Moreover, adjuncts differ from subjects and objects in that there is no limit to the number of adjuncts that can be included in a clause.
2. Position
Objects occur immediately after the verb, with the indirect object before the direct object when both are present (The bomb killed a policeman (Od); He sent me (Oi) an email (Od)). Complements also occur after the verb or after an object. Adjuncts occupy different positions according to type, and are often moveable within the clause.
3. Ability to become the subject
Objects can normally become the subject in a passive clause, since the system of voice allows different semantic roles to be associated with Subject and Object functions (The bomb killed the policeman/The policeman was killed by the bomb; I sent her an email/She was sent an email).
However, passivisation with ‘promotion’ to subject is not a watertight criterion for the identification of object functions. It can be too exclusive and too inclusive. Passivisation excludes from object status NGs following verbs such as fit, which otherwise fulfil the criteria for objects.
Conversely, passivisation can promote to subject NGs that are certainly not objects. Such is the case in the well-known example This bed was slept in by Queen Victoria, derived from the active Queen Victoria slept in this bed, in which this bed is part of a prepositional phrase (PP) functioning as a locative Complement, not as an object. A prepositional phrase has within it a nominal group, however, which increasingly in present-day English is able to become subject in a corresponding passive clause. Examples of this kind, such as The flowerbeds have been trampled on occur when the subject referent is visibly affected by the action, as is the case here, or acquires some importance, as in the case of the bed slept in by Queen Victoria.
4. Realisations of these functions
As participants, Objects are typically realised by NGs and answer questions with what? who? or which? as in What did they carry?
Subject and Object Complements can be realised by Adjective groups (AdjG) (useful ), as in 7a and 7b, or by a NG (a student).
Circumstantial Adjuncts are realised by PPs (drive on the right) or AdvGs (drive slowly) and sometimes NGs (I’ll see you next week). They generally answer questions with where? when? how? why? as in Where does he work? or How did it happen?
