28.In the railroads' prime years，between 1 890 and 1920，there were a few individuals in the
United States，most of them with solid railroading experience behind them，who made a profession
of writing about railroading--works offering the ambience of stations，yards，and locomotive cabs.
(同位语 most of them;定语从句 who made a profession of writing)
在 1890 年到 1920 年间铁路的黄金时期，美国有几个人(他们大多有丰富的铁路经验)以写铁
路题材为职业——作品围绕车站、停车场和机车。
分句 1. there were a few individuals in the United States
分句 2. most of them with solid railroading experience behind them
分句 3. who made a profession of writing about railroading
分句 4. works offering the ambience of stations，yards，and locomotive cabs.
1 是主句
2 和 3 是嵌套
2 作为 1 中 a few individuals 的同位语，对它进一步解释说明
29.On the other hand，when it comes to substantive--particularly behavioral-information，crows
are less well known than many comparably common species and，for that matter，not a few quite
uncommon ones：the endangered California condor，to cite one obvious example.
(特殊结构 for that matter)
另一方面，当涉及实质性的，特别是行为方面的信息时，乌鸦就不如许多比较而言很普通的
鸟类那样为人所知;而且，也不如许多很不寻常的鸟类，举一个明显的例子，如像濒危的加
利福尼亚大秃鹫那样为人所知。
分句 1. when it comes to substantive--particularly behavioral-information
分句 2. crows are less well known than many comparably common species and, for that matter，
not a few quite uncommon ones：the endangered California condor，to cite one obvious example.
1 和 2 是并列， 分句 1 是时间状语， 2 是主句，其中包含插入语结构 以及冒号连接的解释
说明的成分
30.Keen observers and quick learners，they are astute about the intentions of other creatures，
including researchers，and adept at avoiding them.
(并列同位语 keen observers and quick learners)
乌鸦是敏锐的观察家和快捷的学习者，它们对其他生物(包括研究人员)的意图感觉非常敏
锐，并且善于躲开它们。
分句 1. they are astute about the intentions of other creatures，including researchers
分句 2. and adept at avoiding them.
1 和 2 是并列