最紧要的地方或时机critical juncture

• 话说到坎儿上了

  talk about the most vital part

• 我国正处于改革的坎儿上。

  Our country now stands at a critical juncture of reform.

指坏运气或窘迫的处境setback

• 这次可是你的坎儿。

  This is a setback for you.

暗语<方>jargon