hydra

• 名词，有两个不同含义：指难以根除、涉及多方面且难以克服的顽固问题，或指一种小型淡水腔肠动物（水螅）。

A noun with two distinct meanings: a persistent and pervasive problem with many aspects that is difficult to overcome, or a small freshwater polyp.

1. Persistent problemC1formal

   A complex and pervasive difficulty that cannot be solved with a single effort due to its many aspects.

   九头蛇难题

   • The corruption scandal was a hydra that kept revealing new heads.
   • Tackling poverty is a hydra requiring multiple strategies.
   • The company's financial issues were a hydra, with each solution revealing new problems.

   同义词can of wormsmorassquagmiresnake pittangle

2. Freshwater polypB2formalscientific

   A small, tubular, solitary freshwater hydrozoan polyp of the genus Hydra, known for its ability to regenerate.

   淡水水螅

   • The hydra can regenerate an entire organism from a small fragment.
   • Under a microscope, the hydra's tentacles are clearly visible.
   • Biologists study the hydra to understand cellular regeneration.