Greenbaum (1969）mainly studies adverbs syntactically.In comparison, Quirk et al.(1985）illustrate adverbs both syntactically and semantically.In their works, adverbs are divided into adjuncts, subjuncts, disjuncts and conjuncts.Adjuncts and subjuncts are relatively integrated within the structure of the clause.By contrast, disjuncts and conjuncts have a more peripheral relation in the sentence.Semantically, disjuncts express an evaluation of what is being said either with respect to the form of the communication or to its meaning.Bussmann (1996: 306-307）mentions that this evaluation refers to modal aspects, the degree of reality expressed by the utterance (e.g.probably, hopefully, possibly), or some emotional aspects (e.g.luckily, unfortunately, thank God).Conjuncts express the speaker’s assessment of the relation between two linguistic units.The differences in the syntactic functions that different adverbs perform can be illustrated by the following examples:
(46）Slowly they walked back home.(adjunct)
(47）Would you kindly wait for me? (subjunct)
(48）Frankly, I’m tired.(disjunct)
(49）She has bought a big house, so she must have a lot of money.(conjunct)
(50）Ideally, every school should have its own welfare officer.(disjunct)
(51）He smokes a pipe, maybe.(disjunct)
(52）Basically, play leadership is the technique of playground.(disjunct)
In Example (46), the adverb slowly as an adjunct expresses manner, modifying the act of “walked”.In Example (47), the adverb kindly as a subjunct expresses politeness and mainly modifies the MV would though it has impacts on the verb of “wait” as well.In Example (48), the adverb frankly as a disjunct expresses the speaker’s attitude and modifies the proposition of the clause involved.In Example (49), the adverb so as a conjunct just links the propositions of the two clauses before and after it.In Examples (50）and (51), the speakers express their views towards the propositions related to by ideally and maybe respectively.In Example (52), the speaker shows the uncertainty about the action of smoking a pipe by basically.Thus, attitudinal disjuncts may be linked to comments on either the proposition or action conveyed.
Quirk et al.(1985）state that adverbs have the following syntactic functions: as modifiers (of adjectives, adverbs, particles, prepositions, pronouns, etc.), and as complements (of prepositions, e.g.).Quirk et al.’s study on adverbs is comprehensive, for it is based on large corpora.
In Functional Grammar (i.e.the Dutch Functional School）adverbial constructions are generally referred to as satellites.Satellites are like arguments in that they contain a variable and are assigned a semantic function.They differ from arguments only in the fact that they are optional.The Dutch Functional School interprets Quirk et al.(1985）in its own way as listed below in Table 2.2.
According to Hengeveld (2005), the main difference between satellites at the interpersonal level and satellites at the representational level is that the former are speaker-, addressee- or speech act-oriented, whereas the latter are argument- or SoA-oriented (state of affairs-oriented).However, it should be noted that in Quirk et al.(1985）adjuncts and subjuncts are treated separately, while the Dutch School and Greenbaum classify them as adjuncts only (subjuncts are regarded as predicate satellites and adjuncts predication satellites by the Dutch School).Yet, Greenbaum (1969), Quirk et al.(1985）and Hengeveld (2005）all agree that it is mainly disjuncts that express modality.
Sometimes, adverb and adjunct seem to be synonymous; yet, this confusion should be clarified.Morley (2000）thinks that adjuncts can be realized by such syntactic elements as nominal group, adverbial group and prepositional phrase.In another word, adjunct is a functional label while adverb a syntactic one.Also, adverbs are mainly taken as single words that modify predications or clauses and link clauses.In some cases, idiom-like prepositional phrases (e.g.of course, in fact, in any way, etc.）are considered adverbs as well.Adverb is just one of the grammatical means that can function as adjunct.
Morley (2000: 40-50）classifies adverbs into circumstantial adverbs (modifying verbs or nouns, including manner, place and time), intensifiers (regarding the speaker’s perspective on the sentence, labeled as modal or disjunctive adverbs), conjunctive adverbs (providing a connective link between the preceding clause and the present one), and interpersonal adverbs (sentential or inter-clausal adverbs, including politeness or courtesy adverbs, continuity markers, greetings and farewells, polarity and agreement responses,
From the studies on adverbs at the clause level by many linguists (Greenbaum, 1969; Quirk et al., 1985; Hengeveld, 2005), it can be found that MAs are identified with disjuncts that convey the speaker’s judgment or attitude toward a proposition.Yet, Morley (2000）suggests that adverbs other than disjuncts can also function interpersonally.The Dutch Functional School indicates that modal devices, be they MVs or MAs, are assigned to the pragmatic module and function as satellites that can convey speech acts.
2.1.5.2 Discourse level
Some linguists deal with modal devices according to their communicative functions in discourse.They demonstrate that the functions of modal devices can be understood through an analysis of the discourse strategies and ideologies involved.