interjection · an interjection used as a greeting or to call for attention

嗨，你今天过得怎么样？

interjection · an exclamation expressing regret, sorrow, or a sigh

嗨，我也拿他没办法。

interjection · a state of intense excitement or euphoria, natural or drug-induced

昨晚的跨年派对大家都玩得很嗨。