Halliday & Matthiessen (2004: 506-7):
Here the relation of active to passive is different, because the conative verb although not constituting a separate happening, does in fact represent a behavioural process, and it retains its behavioural sense when the clause is passive. …The extending complex is a two-part process, in which the Subject fills a dual participant rôle: Behaver (in the conative component) plus Actor, or some other rôle, in the happening itself.For the same reason, Adjuncts in the clause may relate semantically to the conative component like hard, quickly in she tried hard to write well, she quickly learnt to tell them apart …There is no need in the analysis to tie these structurally to the primary verbal group; but it is useful to specify their function, by labelling them as ‘conative Adjunct’.