preposition, verb, particle, pronoun, adverb, place word, directional, place name, noun, adjective, punctuation, measure word, numeral, suffix · to be located at or in a specific place

我就在学校门口。

adverb, preposition, verb, noun, pronoun, measure word · used before a verb to indicate an action currently in progress

他在写作业。

preposition, adverb, noun, place name, verb, directional, punctuation, abbreviation, pronoun · used to indicate a specific time or place

他必须在五点前完成。

verb, preposition, noun, adverb, punctuation · to exist, be alive, or be present

他爷爷已经不在了。

verb · to consist in or lie in; to depend on

幸福不在于金钱，而在于内心的平静。