Some band fingering charts only show the low C roller as being depressed, but most flutes will leak if you don't depress both keys.

一般的指法表只要求你仅仅按住低音C的滚轮，（但是大多数的长笛都会在C#键漏气）， 如果你不同时按住C 和C#键， 低音C一定会漏气。

youdao

Doctors said her liver enzymes were off the charts and diagnosed her with hepatitis C.

FORBES: Stealth Killer