kernel

杏仁的果仁富含营养。

The ___kernel of an almond is packed with nutrients.

这个理论的核心思想其实很简单。

The ___kernel of this theory is actually quite simple.

每个谣言，无论听上去多么离奇，都蕴含着一丝真相。

There is a ___kernel of truth in every rumor, no matter how outlandish it sounds.