Adverb

• Degree adverbs
• Scope adverbs
• Time adverbs
• Tone adverbs
• Negative adverbs

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
• 又 and 再
  • 又 for past repetition. The event has happened twice.
  • 再 for repetition in the future. The event has happened once so far.
  • 又 may be used for future events if they are definitely going to occur, such as days of the week: 明天又是星期三了.

Sources

• 外国人实用汉语语法(中英文对照) (pp. 105 - 116)