SFL holds that mood adjuncts of temporaltiy (such as yet and already)and intensity (such as surely and totally)convey modality as well.If these adjuncts are combined with MVs and function as MSAs, they offer a background for encoding and decoding the attitudes or judgments conveyed by MVs.In this sense, they play a role of modality supplementing.
The previous studies have revealed that modal co-occurrences do exist and that such co-occurences produce different modal effects in comparison with single modal devices.Since MVs are part of the clause predication, the MSAs that co-occur with MVs must be regarded as expanding the clause predication concerned.Vet (2005: 299-322)holds that utterances in communication are multilayered structures.In this sense, core and nuclear predication tends to be extended or expanded in many ways.Thus, MSAs that accompany MVs should be taken as a means of modality supplementing.According to the Dutch Functional School, such extensions are normally operators or satellites.
Some adverbs co-occurring with MVs should not be considered as MSAs, for they do not indicate modality.Circumstantial and some conjunctive adverbs are in this category.Circumstantial adverbs (labeled as circumstantial adjuncts), according to Thompson (1996: 104-107), essentially encode the background against which the process takes place.There are basically nine main types of circumstantial elements in SFL: location (e.g.in 1937, in London), extent (e.g.for another few miles), manner (e.g.expertly, like a light), cause (e.g.out of curiosity, for her), contingency (e.g.despite his exhaustion), accompaniment (e.g.with her brother), role (e.g.as a referee), matter (e.g.about me), and angle (to Miss Jones).
In SFL, circumstantial adjuncts are analyzed by means of transitivity (experiential construal)rather than mood (interpersonal construal).Thompson (1996: 134-135)indicates that conjunctive adverbs (labeled as conjunctive adjuncts in SFL), such as however, alternatively and as a result, signal how the clause as a whole fits in with the preceding text.
In SFL, conjunctive adjuncts are analyzed by means of textual metafunction instead of interpersonal metafunction.However, it should be noted that some conjuncts like still, therefore and henceforth can convey modality when placed together with MVs, as in must henceforth, should therefore and might still.In another word, conjuncts in these co-occurrences function as both connectors and modal markers.
It boils down that MSAs are normally those adverbs called adjuncts and subjuncts, or modal adjuncts termed according to SFL.However, it should be reminded that some adverbs may function as both modal adjuncts and conjunctive ones.Take the following for instance:
(82)Yet, she would not come even with our invitation.
(83)Still, John could not finish his work even if another three days were given.
Yet and still in Examples (82)and (83)are both conjunctive adjuncts and mood adjuncts of temporality in SFL.If there were no MVs that co-occur with them, these two adverbs could hardly serve as MSAs.Hence, it is reasonable to say that MSAs are parasitic on MVs.Put in another way, some adverbs may not overtly or even do not express modality without the occurrences of MVs.
It should also be noted that MSAs are different from MAs or adverbs in showing modality.This can be confirmed through the co-occurrences of MVs and MSAs.Hoye (1997: 75-76)points out that the co-occurrences of MAs and MVs are strict under some circumstances.For example, may possibly and must certainly are acceptable while *may certainly and *must possibly are unacceptable.The strict requirement for co-occurrences may stem from a variety of reasons.Hoye (ibid)does mention that semantic compatibility may affect the combinations concerned.However, it should be known that other factors also have impacts on the co-occurrences of MVs and MAs.For instance, some co-occurrences may be related to genre or text types.Also, modes of communication (i.e.spoken vs.written)may play an important part in the formation of specific co-occurrences.Furthermore, it is believed that there are restrictions on the combinations between MVs and adverbs that normally do not function modally but do when linked to former.Thus, a theoretical framework concerning the studies on MSAs should be established.