Principal Reasons Large S Civil Rights Long Minority

意群训练： Civil rights activist s have long argue d that one o f the principal reasons why Blacks，Hispanics ，and other minority group s have difficulty establishing themselves in busines s is that the y lack access t o the sizable orders and subcontract s that are generate d by large companies .

标志： Civil rights activists have long argued that one of the principal reasons (why Blacks，Hispanics，and other minority groups have difficulty establishing themselves in business) is that they lack access ［to the sizable orders and subcontracts (that are generated by large companies)］.

译文： 人权活动分子 一直认为 （黑人、拉美裔和其他少数族裔的美国人之所以难以在商界有所作为的）主要原因 就是 因为他们 缺乏得到 ［大规模的订单和 （大公司所产生的）分包合同的］途径 。

解释： 主句简单，宾语从句的结构复杂。从句的主语one of the principal reasons 被由why所引导的较长的定语从句修饰，造成了主语和表语is的分离；is之后又来了个表语从句；其中的宾语被介词结构所修饰，而介词结构中的由and连接的第二个介词宾语subcontracts又被定语从句（that are generated by large companies）修饰，是典型的从句套从句的层层修饰。