1.a dog in the manger占着茅坑不拉屎的人

　　出自《伊索寓言》(Aesop's Fables)，有一篇狗站马槽的故事，说的是一头狗躺在堆满稻草的马槽里，狗是不吃草的动物，而当马或牛一走进稻草时，这头狗却朝着马，牛狂哮，不准食草动物享用。

　　因此，“狗站马槽”就成了一个家喻户晓的成语而进入英语中，常用来比喻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，讽刺那些占据说职位或某些物质却不做事的人。

　　a dog in the manger是个名词性短语，常与系动词连用，充当表语(主语补足语)

　　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.

　　2.bell the cat自告奋勇去冒险；老虎头上拍苍蝇

　　bell the cat系成语to hang the bell about the cat's neck的简略，愿意是“给猫的脖子上挂铃”。它来自《伊索寓言》(Aesop's Fables)中的《老鼠会议》(The Mice in Council)

　　这篇寓言讲的是：一群老鼠在鼠洞里举行会议，讨论如何对付凶狠的猫。白胡须老鼠提出：“我有个方法，在猫的脖子上挂一个铃。这样，猫一走动铃就响，我们就可以闻铃声而逃避了”，群鼠一致同意这个建议，欢呼：“That's a capital idea.We will bell the cat!No more fear of the cat!”但是，谁去给猫挂铃铛呢？没有一只老鼠敢去，一个个都溜掉了。老鼠会议豪无结果，它们不安全的境况当然也无法改善。

　　寓言所寄托的意思很明白：遇到困难的问题时候，既需要有出谋献策的人，更需要有挺身而出的实干家。

　　bell the cat常用来比喻to do sth dangerous in order to save others;to step forwar bravely to face the danger;to take a risk for the good of others.

　　eg:Everybody made suggestion,but no one actually offered to bell the cat.

　　We didn't know who would put him this delicate question when my friend offered to bell the cat.

　　3.cry wolf虚发警报；慌报险情；危言耸听

　　cry wolf来自《伊索寓言》：《牧童和狼》 (The Shepherdboy and the wolf)

　　有个牧童在离村子不远的山坡上放羊，有一次，他为了开心作乐，突然大喊：“Help!Help!The wolf!”全村的人都闻声跑来援助他时，才知道这只是开玩笑。如此恶作剧搞了两三次。后来，狼真的来了，那个牧童再呼号求救时，谁也不理会他了。于是，狼把他的羊吃了。

　　这篇寓言的意义很清楚：爱说谎话的人，即或在他说真话时，也没人相信他。由此，人们用to cry wolf 来概括这篇寓言的基本情节及其教诫意义，用以比喻to give false alarms;to warn of danger where there is none之意。按其比喻意义，这个成语相当与汉语中出自《东周列国志》的典故：烽火戏诸侯。周幽王为博得宠妃褒泥一笑，竟然把军国大事当儿戏，烽火报警戏诸侯，使各路诸侯仓促发兵，驰援京师，结果收到嘲笑。后来犬戎进犯，幽王再举烽火调兵，谁也不来了，结果周幽王遭到杀身亡国之祸。这2个典故的情节虽不同，寓意却完全不一致，都是表示“一朝说假话，一世无人信”

　　eg:Nobody will believe he is in trouble because he has cried wolf so many times.

　　Is she really sick of is she just crying wolf?

　　The newspaper placards that had cried "wolf" so often,cried "wolf" now in vain.