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 railroadingexperience behind them，who made a profession of writing about railroading--works offeringthe ambience of stations，yards，andlocomotive 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. whomade a profession of writing about railroading

分句4. works offering the ambience of stations，yards，andlocomotive 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