三人行，必有我师(焉)

语法
...究竟 + 是 + ..., "after all, X is X" (bottom of page)
https://resources.allsetlearning.com/chinese/grammar/Expressing_%22in_the_end%22_with_%22jiujing%22

词汇
健康, health (pinyin in tags)
https://mandarinbean.com/new-hsk-2-word-list/

Guardian:
[no 究竟 of this kind]
我那有无烟的，环保又健康, I have a smokeless one, eco-friendly and healthy
你看我身体健康意志坚定, look, I'm healthy and I'm determined

Me:
今天比较凉快了，但是夏天究竟是夏天，明天再热了吧。
对他的健康你有什么担心？