Dead as a doornail
像门钉一样死了？门钉被钉在门上就无法移动，从此就死气沉沉了。英语中，dead as a doornail表示“死掉了”或者“没用了”。

例：He shot the tiger until it was as dead as a doornail.
他不断朝那只老虎射击，直到确信它已经死绝了.
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来背背例句吧~