青春大概: Reflecting Youth | Wang Shang

This song describes looking back on the times of youth and is sung a lot at graduations or at performances during high school/ university. Here's one example from the graduation ceremony of QingDao Uni : https://www.youtube.com/watch?v=ijlKz2L4Dws
Also, at
00:36
This line references an idiom 细水长流. It is a metaphor for the economical use of property, so that it is often not in short supply. It is also a metaphor for doing something uninterrupted bit by bit, finely arranged, and long-term planning. It also refers to a long-lasting love or friendship (which is probably the meaning used in this song).
03:28
但我相信共你 没有白活。
但: but, 我相信: I believe/ I trust, 共 means 'with' or 'accompanied by', 你: you, 没有白活 refers to not having lived in vain.

歌：《青春大概》
演唱：王上
词：彭錞
曲：徐鸣涧