Leg 是名词，意思是“腿”，所以 leg up 虽形似短语动词，但实际上不是，而且它虽包含 leg，但实际的意思也跟腿没有直接关系。 Leg up，也作 leg-up， 是一个习语，从字面上理解是别人的推动或帮忙使一个人登上更高的物体、墙或马等，可以意为“用双手托脚帮助（某人上马、翻墙等） ”，例如：Give me a leg up so I can reach the dishes on the top shelf.托我一把，这样我就能够碰到最上面架子的盘子了。I gave her a leg up, and soon she was on her horse.我助她一臂之力，很快她就骑上了马。因此它也用来比喻因为某些因素使某人实现某个目标或处于优势地位等，常用于句型：give sb/sth a leg up，例如：A recent ruling will give terrestrial broadcasters a leg up in competing with satellite radio.最近的一项裁决将使地面广播公司在与卫星广播的竞争中获得优势。Completing the summer study program gives pupils a leg up in the following academic year.完成暑期学习计划可以让学生在下一学年有更大的进步。Speaking three languages certainly gave Laura a leg up in the interview for the promotion.劳拉会说三种语言，这无疑使她在升职面试中占了上风。Leg up 还可以用来比喻在某种情况下处于优势地位，或比别人有优势，常用于句型：have a leg up on，例如：I knew I had a leg up on my opponent when I saw that he was struggling to counter my opening moves.当我看到我的对手在努力反击我的开场动作时，我知道我比他强多了。Because of the advertising campaign, we had a leg up on the competition.由于广告宣传，我们在比赛中占了上风。
与 leg 对应的 hand 也有一个习语 a helping hand，它也可以表达一臂之力，例如：1. 常用于搭配 need/get a helping hand，表示需要帮助，例如：I could really use a helping hand carrying all of these boxes downstairs.我真的需要一个帮手把这些箱子搬下楼。When you feel like you need a helping hand making dinner, just let me know.当你觉得你需要帮忙做晚餐的时候，就告诉我。You've been such a helping hand with this dinner, I couldn't have done it without you!
你帮了我这顿饭，没有你我是办不到的！
2. give/lend/offer sb a (helping) hand，表示帮助某人，相当于 help sb，例如：Come and give me a hand in the garden.到花园里来帮我一把。These tax cuts will give industry a helping hand.这些减税措施将有助于工业界。The Federal Reserve is expected to lend a hand by continuing to cut interest rates forcefully.大家希望美联储将继续大力降息以助一臂之力。I was going to ask him to lend me a hand when he came just in time.我正想找他来帮帮忙，可好他来了。需要引起注意的是 give sb a helping hand 与 give sb a big hand 意思完全不一样，give sb a big hand 是热烈欢迎某人的意思，例如：Let's give our special guest a big hand!让我们为我们的特别客人热烈鼓掌！Ladies and gentlemen, let's give a big hand to our special guests tonight.女士们先生们，让我们以热烈的掌声欢迎今晚的特邀嘉宾。那么从被欢迎的人的角度来表达就是 get a big hand，例如： This speaker always gets a big hand.这个演讲者总是很受欢迎。Mr Wells got a big hand from most of the people present.威尔斯先生得到了在场大多数人的热烈欢迎。词或词组辨析：terrestrial [təˈrestriəl] 意为“陆地的，地面上的”等
