white elephant

 Longman Dictionary of Contemporary English 5++朗文当代英语 5++LDOCE 5++朗文 5++ˌwhite ˈelephant noun [countable]  USELESSsomething that is completely useless, although it may have cost a lot of money 昂贵而无用的东西 When the theatre first opened it was widely regarded as a white elephant. 那家剧院刚开张时，大家都认为它是个奢侈的摆设。

Examples from the Corpus

white elephant• Saracen ambassadors bring Charlemagne a white elephant complete with exotic trappings.• The dam has become something of a white elephant.• Cake and white elephant stalls plus a grand prize draw.• More spaces are needed at less cost not another white elephant office block.• What do you do with a huge white elephant like that?• There's this picturesque white elephant development on the Costa del Sol, apparently going for a song.From Longman Business Dictionarywhite elephantˌwhite ˈelephant noun [countable] something that is completely useless, even though it cost a lot of moneyThe hotel is unfinished and structurally unsound - a white elephant of epic proportions.Origin white elephant (1800-1900) From the supposed practice of the King of Siam, who gave to people he did not like a white elephant, which cost a very large amount of money to keep

ˌwhite ˈelephant nounChineseSyllable  

that is something completely useless, although Corpus Business it

white elephant
ˌwhite ˈelephant noun [countable]something that is completely useless, although it may have cost a lot of money:
    When the theatre first opened it was widely regarded as a white elephant.

white elephantBrE /ˌwaɪt ˈelɪfənt/ 🔊NAmE /ˌwaɪt ˈelɪfənt/ 🔊 noun [usually singular] a thing that is useless and no longer needed, although it may have cost a lot of money 昂贵而无用之物◆The new office block has become an expensive white elephant. 这座新办公大楼成了昂贵的摆设。🔊🔊 ORIGIN From the story that in Siam (now Thailand) the king would give a white elephant as a present to somebody that he did not like. That person would have to spend all their money on looking after the rare animal. 源自暹罗（今泰国）的一个故事。当时的国王会送白象给他讨厌的人，让这个人不得不花掉所有的钱来照顾这种稀有的动物。