The structure of Adverbial phrase

Some adjectives can be modified by constituents they do not select. In this case their relation to the adjective is frequently reducible to a causal relation (as in happy to hear from you); or to some kind of comparison [syntax- Section 3.6; Semantics- Chapter 8] (as in red as a tomato). Here again very little is known for sign languages, and the form, order and restriction of these constituents should be looked at with care.Adverbial phrases are constituents headed by [Lexicon- Section 3.5], not to be confused with adverbial clauses [Syntax- Section 3.5; Semantics- Section 14.2], which are sentences that are constituents of a complex sentence. Adverbial phrases (in bold in the following examples) are adjuncts, and as such may modify an adjective (a), another adverbial (b), a clause (c) or a verb (d) by providing information regarding the grammatical categories of [Semantics- Chapter 1; Morphology- Section 3.2] (yesterday), [semantics- Chapter 2; Morphology- Section 3.3] (already), and [Semantics- Chapter 4; Morphology- Section 3.4] (necessarily, probably) or information regarding manner (proudly) and place (here). They typically answer questions like how? where? when? how frequently? to what extent? a. He was quite clear b. The children spoke very loudly c. John’s horse certainly will win the race d. John’s horse will quickly pace towards the finish line