I have a contract for two million dollars a year to plug these shoes on TV. They've already filmed three plugs and you'll see the first plug next week - I think you'll like it.

　　我有一份耗资两百万美元为这些鞋子作一年电视广告的合约。他们已经拍了三个广告片。下星期你将会看到第一个。我想你会喜欢的。

　　例句里提到 to plug these shoes，这里plug是动词，就是“做广告宣传”。后面提到的 three plugs和the first plug，这里plug成了名词了，意思就是“广告”。

　　2. plug away 坚持不懈，努力完成某项工作

　　I started my novel five years ago. It's been hard to find the time with all my other work, but I've kept plugging away every weekend and yesterday I started the last chapter.

　　我五年前开始动笔写这部小说。但是因为平时还得忙于其它事务，所以很难挤出时间来写作。不过，我每个周末都坚持创作，昨天已经开始进入最后一章的写作了。

　　这里的plugging away every weekend就是每个周末都埋头苦干的意思。五年来一直如此。这样说来习惯用语plug away意思就是坚持不懈、排除障碍，努力完成一件困难的工作。

　　3. plug in 和权贵关系密切并熟知内情

　　See that tall man who just walked in. He's a good news source: he's a lawyer who's plugged in to the leaders of both political parties and is really in touch with what's going on.

　　看见那刚进来的高个子先生吧，他可是宝贵的消息来源。他是律师，和两党的头面人物都关系密切，所以确实熟知政界内情。

　　我们都知道plug通常可以指电线插头，动词词组plug in意思一定是“插进插头”。电器一插上了插头就接通了电源，也就能发挥作用了。然而plug in常常隐含更深的意思，可以转用来说人，多用be plugged in to的形式出现，表示“和权贵/高层关系密切并熟知内情”。