He had never gambled before the casino sent him a coupon for $20 worth of gambling.

参考译文：在赌场寄给他一张价值为$20赌资代金券之前他从没有赌过。

【1】主句:He had never gambled.【主语+谓语动词】

主句语法结构为：He【主语】// had never gambled【谓语动词】.

【2】从句:before the casino sent him a coupon for $20 worth of gambling.

【从属连词before 引导的时间状语】

从句语法结构为： before【连词】// the casino【主语】// sent【谓语动词】// him【间接宾语】// a coupon【直接宾语】// for $20 worth of gambling【后置定语】//.

备注(1):在名词短语$20 worth of gambling中，worth为名词用法“价值”结构为“金钱+worth of sth=价值为多少钱某物”, for $20 worth of gambling为介词短语作定语修饰coupon.    worth为中心名词，作介词for的宾语，$20 为worth前置定语，of gambling为介词短语作worth的后置定语。be well worth doing很值得做某事。worth有的字典为形容词，有的字典为介词。什么词性不重要，重要的是会使用。

I am willing to buy £100,000 worth of bonds.我愿意购买价值10万英镑的债券。

He wins £100 worth of Phoenix 2000 fish food.他赢得了价值100英镑的凤凰城2000年鱼粮。 

The winner will receive ten pounds' worth of books.获胜者将得到价值十英镑的书籍。

I went and bought about six dollars' worth of potato chips.我去买了大约6美元的薯条。

备注(2):worth 为形容词/介词 有…价值；值…钱 结构：主语+be worth+金钱

Our house is worth about £100 000.我们的房子大约值10万英镑。

How much is this painting worth?这幅画值多少钱？

These books might be worth £80 or £ 90 or more to a collector.

这些书对收藏家而言可能值八九十英镑或更多。

His mother inherited a farm worth 15,000 dollars a year.

他母亲继承了一处年产值为1.5万美元的农场。