An Adjunct “is an element that has not got the potential of being Subject; that is, it cannot be elevated to the interpersonal status of modal responsibility…typically realized by an adverbial group or a prepositional phrase” (H & M, p.123-4). For a prepositional phrase, consisting of a Predicator + Complement, it is often the case that one of the constituents, the Complement, has the potential of becoming a Subject and the preposition gets left behind. For example, in the clause someone’s already written on that paper, on that paper functions as Adjunct but it is also possible for the noun group that paper to function as Subject, in which case on is left behind:
|that paper||‘s||already||been written||on|
There are three types of Adjunct which can be distinguished by metafunction. This affects their location in the clause:
- circumstantial Adjuncts, which are located in the Residue (experiential metafunction);
- modal Adjuncts, which may be in either Mood or Comment (interpersonal metafunction);
- conjunctive Adjunct, which are not located in the mood structure (textual metafunction).
For EFL, this metafunctional distinction between the types of Adjuncts is important and explains why the common EFL exchange Q: How often do you play tennis? – A: Usually sounds unnatural. The question how often is experiential in nature and thus would most naturally take a circumstantial Adjunct (once a week). The mood Adjunct usually, however, is interpersonal in nature and indicates part of the speaker’s attitude towards the activity. This explains why the exchange Q: Do you like tennis? – A: Sometimes, I guess could be judged as acceptable but is often not seen as such by EFL learners.