每日一句

The United States is the product of two principal forces—the immigration of European peoples with their varied ideas, customs, and national characteristics and the impact of a new country which modified these traits.

词汇突破

principal
adj. 主要的；资本的
n. 首长；校长；资本；当事人
immigration 
n. 外来移民；移居
immigrate
v.（从外地）移居，移民；使移居入境

结构分析

本句的主干是 The United States is the product of two principal forces，该句是主系表结构的简单句，the immigration of European peoples with their varied ideas, customs, and national characteristics and the impact of a new country which modified these traits 为 two principal forces 的同位语，其中心成分为 the immigration and the impact，which modified these traits 为限制性定语从句，修饰先行词 a new country。

参考译文

美国是两股主要力量的产物：一股是思想、习俗、民族特性各异的欧洲移民的迁入，另一股是新成立的国家在改变这些特征后产生的影响。