Adverb

Potential content

Can't be reduplicated (although reduplicated adjectives can be converted into adverbs with 地, e.g. 急急匆匆地).
Can't be used as answers to questions.
Can't modify nouns.
Can't precede subjects (in general).
Some adverbs can function as linking words (conjunctions). E.g. 就
Always appear before a verb or adjective.
都
也
Difference between:
- 原来, 本来
- 不必, 未必, 何必
- 不免, 难免
- 毕竟, 到底，究竟
- 就, 才
- 差点儿, 几乎
- 常常, 往往
- 从来, 始终
- 倒, 反而
- 多亏, 幸亏
- 分明, 明明
- 赶紧, 赶快, 赶忙, 连忙
- 刚, 刚刚, 刚才
- 果然, 竟然, 居然
- 好像, 似乎
- 突然, 忽然
- 千万, 万万, 万一
- 太, 挺, 真
- 特别, 尤其
- 偷偷, 悄悄
- 一点儿, 有点儿
- 一直, 总是
- 只好, 不得不

Some adverbs can be used as answers to questions, such as 不, 没有, 也许 and 可能 etc.
Nearly all adverbs occur as adverbials (in front of the verb) but a couple can occur as complements (after the noun), such as 极了 and 得很.