每日一词学英语(8): what's the catch

看到一个新闻标题：A&L offer ￡100 and a free overdraft: what's the catch?

在what's the catch那儿愣了一会儿，查了趟字典，回来一看，原来解释在正文第一段就有：

Alliance & Leicester (A&L) is once again offering its ￡100 switching incentive with both its Premier Current Account and the Premier 50 Current Account. The deal is available until the end of May, but is it too good to be true?

is it too good to be true和what's the catch是一个意思。写文章比较忌讳一个意思用同一个词翻来覆去的说，那样的文字不会有文采。对学外语的人这倒是个好处，不认识的词可以由此猜出意思来，因为在作者多次变换使用的几个词中，总会有简单些的；有些情况下这个简单词不是近义词，是反义词，你自己脑子里把意思反一下就行了。

言归正传。catch在这里的意思是陷阱、欺诈，Wikitionary上的解释是：

(countable, sometimes noun adjunct) A concealed difficulty, especially in a deal or negotiation.

It sounds like a great idea, but what's the catch? 听起来很好，别有什么圈套吧？
Be careful, that's a catch question. 你可要当心，那个问题是个套儿。

说到catch不能不提Joseph Heller的代表作，长篇小说Catch-22(《第22条军规》)，由此引出逻辑学和博弈论中的“双输情况”("no-win" or "lose-lose" situation)。No choice leads to a net gain. 你可要当心！