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a dog in the manger 占著茅坑不拉屎的人
出自《伊索寓言》(Aesop's Fables)，有一篇狗站馬槽的故事，說的是一頭狗躺在堆滿稻草的馬槽里，狗是不吃草的動物，而當馬或牛一走進稻草時，這頭狗卻朝著馬，牛狂哮，不準食草動物享用。
因此，“狗站馬槽”就成了一個家喻戶曉的成語而進入英語中，
常用來比喻??a person who prevents others from enjoying sth that is useless to himself;
a churlish fellow who will neither use a thing himself nor let others use it，
諷刺那些占據(jù)說職位或某些物質(zhì)卻不做事的人。
a dog in the manger是個名詞性短語，常與系動詞連用，充當表語(主語補足語)
eg: He borrowed a lot of books from the library,but he didn't read a book.
He was really a dog in the manger.
There are some officials who are only the dogs in the manger.
Smith was a dog in the manger over that roll of wire;it was no use whatever to him,but he wouldn't let us have it.
