As hard as nails
这个短语字面解释是“像钉子一样坚硬”。我们知道钉子是用铁或者其他非常坚硬的材料做成的。如果一个人像钉子一样硬的话,那人想必既顽固强硬又无情无义,是个相当难相处的人。
请看例句:
They offered me a good job at that company but I hear that the boss is as hard as nails:one little mistake and you're out on the street the next day looking for a new job.
那家公司向我提供了一个很好的职位,但是我听说他们的老板是以毫无情意的人:只要你犯一个小错,他就马上把你一脚踢出公司大门,让你令谋生路。