adverb

An adverb is a word or an expression that modifies a verb, adjective, another adverb, determiner [限定词, the, some, my. 冠词article], clause [从分子句], preposition [介词，不是proposition], or sentence. Adverbs typically express manner, place, time, frequency, degree, level of certainty, etc., answering questions such as how?, in what way?, when?, where?, and to what extent?. [wh-questions] Adverbs are traditionally regarded as one of the parts of speech [词性]. The English word adverb derives (through French) from Latin [拉丁文] adverbium, from ad- ("to"), verbum ("word", "verb"). The term implies that the principal function of adverbs is to act as modifiers of verbs or verb phrases. Some examples:
- She sang loudly.
- We left it here.
- I worked yesterday.
- You often make mistakes.
- He undoubtedly did it.

Adverbs can also be used as modifiers of adjectives, and of other adverbs, often to indicate degree. Examples:
- You are quite right.
- She sang very loudly.

They can also modify determiners, prepositional phrases, or whole clauses or sentences, as in the following examples:
- I bought practically the only fruit ("only" is an adjective)
- She drove us almost to the station (almost modifies the prepositional phrase to the station)
- Certainly we need to act (certainly modifies the sentence as a whole)

Because some adverbs and adjectives are homonyms [同形同音异义词], their respective functions are sometimes conflated [混合]:
- Even numbers are divisible by two.
- The camel even drank.
The word "even" in the first sentence is an adjective. The word "even" in the second sentence is a prepositive adverb [介词副词] that modifies the verb "drank." A prepositional phrase [介词短语] is a a phrase beginning with a preposition. Examples are 'in bed' and 'by the sea'.

Although it is possible for an adverb to precede or to follow a noun or a noun phrase, the adverb nonetheless does not modify either in such cases, as in:
- Internationally there is a shortage of protein for animal feeds.
- There is a shortage internationally of protein for animal feeds.
- There is an international shortage of protein for animal feeds.

In the first sentence, "Internationally" is a prepositive adverb that modifies the clause, "there is ..." In the second sentence, "internationally" is a postpositive adverb that modifies the clause, "There is ..." By contrast, the third sentence contains "international" as a prepositive adjective that modifies the noun, "shortage."

Adverbs can sometimes be used as predicative expressions [表语，谓词性表达，哈哈]. 'predict' and 'predicate' are two different words. In English, this applies especially to adverbs of location:
- Your seat is there.
- Here is my boarding pass. (wherein "boarding pass" is the subject [主语] and "here" is the predicate in a syntax [谓语] that entails a subject-verb inversion).

When the function of an adverb is performed by an expression consisting of more than one word, it is called an adverbial phrase or adverbial clause, or simply an adverbial.

In English, adverbs of manner (answering the question how?) are often formed by adding -ly to adjectives, but flat adverbs (such as in drive fast, drive slow, and drive friendly) have the same form as the corresponding adjective. Many other adverbs, however, are not related to adjectives,they may be derived [派生] from other words or phrases, or may be single morphemes [boys由boy和y两个词素构成]. Examples of such adverbs include here, there, together, yesterday, aboard, very, almost, etc.

Where the meaning permits, adverbs may undergo comparison, taking comparative and superlative forms. This is usually done by adding more and most before the adverb (more slowly, most slowly), although there are a few adverbs that take inflected forms, such as well, for which better and best are used.

Grammarians [语法学家] find difficulty categorizing negating words, such as the English not. Although traditionally listed as an adverb, this word does not behave grammatically like any other, and it probably should be placed in a class of its own.

In Chinese, adverbs end in the word "地（的）".

Japanese forms adverbs from verbal adjectives by adding /ku/ (く) to the stem (haya- "rapid" hayai "quick/early", hayakatta "was quick", hayaku "quickly") and from nominal adjectives by placing /ni/ (に) after the adjective instead of the copula /na/ (な) or /no/ (の) (rippa "splendid", rippa ni "splendidly").

In Korean, adverbs are commonly formed by replacing the -다 ending of the dictionary form of a descriptive verb with 게. So, 쉽다 (easy) becomes 쉽게 (easily). They are also formed by replacing the 하다 of some compound verbs with 히, e.g. 안녕하다 (peaceful) > 안녕히 (peacefully).

In Persian, many adjectives and adverbs have the same form such as "خوب", "سریع", "تند" so there is no obvious way to recognise them out of context. The only exceptions are Arabic adverbs with a "اً" suffix such as "ظاهراً" and "واقعاً".