19. The adverb as a part of speech. Morphological composition of English adverbs.

The adverb is a part of speech which expresses some circumstances that attend an action or state. The adverb has no morphological properties that may be regarded as specifically adverbial and be used as a criterion to define its morphological status. Absence of inflections is not restricted to adverbs only; degrees of comparison do not cover all the members of this part of speech; only some adverbs are formed by the derivational suffix -ly.