词汇与表达：plum-plumb-plummet-plunge

plumb

Man's capacity to plumb the truth.

人类探索真理的能力。  

This thing has plumb worn me out.  

这件事让我筋疲力尽。  

plum 李子、葡萄干
plummet
Share price plummet or plunge on the news of the devaluation.
一有贬值的消息，股票价格就暴跌了。

plunge:http://www.etthink.com/thread-284278-1-1.html