1U.S. customers historically tipped people they assumed were earning most of their income via tips, such as restaurant servers earning less than the minimum wage.
主干主语：U.S. customers；谓语：tipped；宾语：people
结构主句后接省略关系代词的定语从句 they assumed were earning...，修饰 people；assumed 后又接省略 that 的宾语从句。such as 引出同位举例，其中 restaurant servers 带现在分词短语 earning less than the minimum wage 作后置定语。整体是“主谓宾+定语从句+举例分词”的层层修饰。
译文美国顾客历来会给那些他们认为主要靠小费谋生的人小费，比如收入低于最低工资的餐厅服务员。
考点省略关系代词的定语从句 people (whom) they assumed... · such as 后接名词+现在分词作后置定语
2Today’s tip requests are often not connected to the salary and service norms that used to determine when and how people tip.
主干主语：Today’s tip requests；谓语：are not connected；介词宾语：the salary and service norms
结构主句为被动结构 be connected to。that 引导定语从句修饰 norms；从句中 used to determine 后接 when and how 引导的宾语从句，作 determine 的宾语。考点在于定语从句套宾语从句，以及 used to 表过去习惯。
译文如今的小费请求，往往已不再与过去决定人们何时、如何给小费的薪资和服务惯例挂钩。
考点be connected to 的被动搭配 · 定语从句中嵌套 when/how 宾语从句
3Tipping has always been a vital source of income for workers in historically tipped services, like restaurants, where the tipped minimum wage can be as low as US $2.13 an hour.
主干主语：Tipping；谓语：has been；表语：a vital source of income
结构主系表结构后接 for workers... 介词短语；like restaurants 为插入举例。where 引导非限制性定语从句修饰 restaurants（或 tipped services），从句中 as low as 表程度。注意 historically tipped 是过去分词作前置定语。
译文小费向来是传统收取小费行业（如餐饮）从业者的重要收入来源，这些地方的小费最低工资可低至每小时 2.13 美元。
考点where 非限制性定语从句修饰地点/行业 · as low as 表下限
4To ensure that all employees were paid fair wages, some restaurants banned tipping and increased prices, but this movement towards no-tipping services has largely fizzled out.
主干主语：some restaurants；谓语：banned... and increased...；后一分句主语：this movement；谓语：has fizzled out
结构句首不定式 To ensure that... 作目的状语，that 引导宾语从句。主句为并列谓语 banned and increased。but 连接转折分句；towards no-tipping services 介词短语修饰 movement；fizzle out 为不及物短语动词。
译文为确保所有员工都能拿到合理工资，一些餐厅取消了小费并提高了菜价，但这一“无小费服务”的潮流已基本偃旗息鼓。
考点不定式目的状语 + that 宾语从句 · fizzle out 表示逐渐失败、不了了之
5And, as our research emphasizes, tipping now seems to be more coercive, less generous, and often completely dissociated from service quality.
主干主语：tipping；谓语：seems to be；表语：more coercive, less generous, and ... dissociated
结构as our research emphasizes 为 as 引导的非限制性定语从句/插入评注，修饰整句。seems to be 后接三个并列表语：比较级 more/less + 形容词，以及过去分词 dissociated from...。often completely 为程度状语。
译文而且，正如我们的研究所强调的，如今的小费似乎更具强迫性、更少慷慨意味，并且常常与服务质量完全脱钩。
考点as 引导评注性从句 · seem to be + 并列形容词/分词表语