pith

她几句话就抓住了演讲的核心内容。

She captured the ___pith of the speech in just a few words.

橙子的白色部分有点苦，所以我总是把它去掉。

The white ___pith of the orange is a bit bitter, so I always remove it.

制作标本时，我们需要先小心地剔除植物的茎髓。

When making specimens, we need to carefully ___pith the plant stems first.