美国流行口语之商务篇

该语的字面意思是“大拇指的规则”，实际意义为“（根据实际经验和实践的）对事物粗略但实用的估计方法”。其出典有两种说法：一说源自旧时用拇指大略计算长度的做法；另一种说法源自昔日酿酒工人将拇指浸在所酿酒中估计温度的做法。

A: Do you think it’s a good idea to buy some traveler’s checks? 你认为买旅行支票是个好办法吗？
B: Definitely! Don’t carry large amounts of cash with you when you’re traveling. We have a rule of thumb: never carry around any more cash than you can afford to have stolen. To be on the safe side, you’d better ask for smaller denominations: $20 or $50. 没错。旅行时不要随身带大额现金。我们有个经验之法：随身携带的钱要适量，丢了不要紧。为了稳妥起见，你最好要小面额的：20或者元。
A: I was told that if you use traveler’s checks, you don’t countersign the check until the clerk in the store is watching you. 我听说在使用旅行支票时，要当着商店售货员的面签字。
B: Yes, you’ve got it. 你说得对.