问个GWD上的语法题。

Until the
passage of the Piracy and Counterfeiting Amendments Act in 1982, a first-time
charge of copyright infringement was merely a misdemeanor charge, federal
prosecutors being unlikely in pursuing criminal copyright infringers, while
offenders were subject to relatively small penalties.

答案是：

charge; therefore, federal prosecutors were
unlikely to pursue criminal copyright infringers, and offenders were

想问： 分号后面为什么可以加上therefore？？ 分号左右不应该是并列句吗？这个明显有逻辑关系啊？？