The adverbial of manner and the adverbial of measure and degree

The adverbial of manner shows how an action is done and answers «как? каким образом?». It is mostly an adverb of manner: «быстро, ловко, внимательно, красиво, метко». Most such adverbs are made from adjectives with «-о»: «тихий — тихо, нежный — нежно, смелый — смело». So the adverbial looks like the neuter form of the adjective, but it explains the verb, not a noun: «пел громко» (how did he sing?) versus «громкая песня» (what kind of song?). Some set phrases also show manner: «на скорую руку» — quickly and carelessly, «засучив рукава» — eagerly, «как снег на голову» — suddenly, «так себе» — so-so, poorly.