nub

名词 nub:

1. a small lump or protuberance
   同义词：nubble
2. a small piece
   同义词：stub
3. the choicest or most essential or most vital part of some idea or experience
   同义词：kernel, substance, core, center, essence, gist, heart, heart and soul, inwardness, marrow, meat, pith, sum, nitty-gritty

1. That's the nub of it.
   关键就在这里。
2. The nub of the problem is our poor export performance.
   问题的关键是我们出口贸易方面太差。