若水

在Wiki查作業的時候看到的

意謂：某某東西有諸多優點　但因為有個很大的缺點（所以沒有被廣泛使用）
xxx is its Achilles' heel



以下轉自
http://www.phrases.org.uk/meanings/23400.html

Meaning
A weak or vulnerable factor.

Origin
The legend of Achilles has it that he was dipped into the river Styx by his mother Thetis in order to make him invulnerable. His heel wasn't covered by the water and he was later killed by an arrow wound to his heel.
Although the legend is ancient, the phrasewasn't picked up in English until the 19th century. It is used as ametaphor for vulnerability, as in the earliest citation, an essay bySamuel Taylor Coleridge in The Friend; a literary, moral and political weekly paper, 1810:

  "Ireland, that vulnerable heel of the British Achilles!"