美國(guó)人在打棒球時(shí)經(jīng)常喜歡發(fā)曲線球，使球的方向會(huì)發(fā)生突變，這樣給對(duì)方造成錯(cuò)覺，不能回?fù)裟莻€(gè)球。這和其他球類運(yùn)動(dòng)，如排球、乒乓球或網(wǎng)球，在發(fā)球時(shí)發(fā)轉(zhuǎn)球的作用也很相似。逐漸地，這種讓對(duì)方產(chǎn)生錯(cuò)覺、因而無法應(yīng)付的球藝變成了日常用語：to throw a curve。
    Curve就是“曲線”的意思。To throw a curve就是“在打棒球時(shí)發(fā)曲線球”。但是作為俗語，它的意思是“給別人造成錯(cuò)覺，讓他難以應(yīng)付”。下面是一個(gè)剛剛考完歷史的學(xué)生在埋怨他的教授：
    Professor Green certainly threw us a curve today. Half the questions were from parts of the book he told us to read but he never covered them in class. Of course, most of us didn't bother to read the stuff, so we really got caught.
    格林教授今天可真是把我們難住了?？碱}的一半是他要我們看的那本書里的內(nèi)容，可是他從來也沒有在課堂上講過。我們大多數(shù)人也都沒有花時(shí)間去看那玩意兒，所以今天我們突然發(fā)現(xiàn)無法應(yīng)付考題了。
    To throw a curve還可以解釋為“欺騙”，下面就是一個(gè)例子：
    My supervisor threw me a curve when he told me he would recommend me for the promotion. He didn't tell me he was also recommending three other people for the same job. So I didn't get it.
    我的上司欺騙了我，他告訴我他要建議給我提升?？墒?，他沒有告訴我他同時(shí)還推薦了另外三個(gè)人擔(dān)任同一個(gè)職位。結(jié)果我沒有被提升。