[求助]逗号+and问题

190.       (30034-!-item-!-188;#058&004766)       (GWD-28-Q24)

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.

A. charge, federal prosecutors being unlikely in pursuing criminal copyright infringers, while offenders were

B. charge, with federal prosecutors who were unlikely to pursue criminal copyright infringers, offenders being

C. charge, federal prosecutors unlikely to pursue criminal copyright infringers, while offenders were

D. charge; therefore, federal prosecutors were unlikely in pursuing criminal copyright infringers and offenders being

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

191.       (26866-!-item-!-188;#058&002042)       (GWD-10-Q24)

For the last five years the Dutch economy has grown faster than Britain, France, or Germany, with the unemployment rate having remained well below that of the other three countries. 

A. Britain, France, or Germany, with the unemployment rate having remained

B. have those of Britain, France, or Germany, and the unemployment rate remaining

C. have Britain, France, and Germany, and the unemployment rate has remained

D. the economy of Britain, France, and Germany, with the unemployment rate that has remained

E. the economies of Britain, France, and Germany, and the unemployment rate has remained

两句话里面的and前面的逗号可否省略？and连接前后句子，什么时候必须在它前面加逗号？？

可以在置顶帖里查询run-on sentence的用法: http://forum.chasedream.com/dispbbs.asp?boardID=23&ID=81945&page=1

具体参见这个帖子：http://forum.chasedream.com/dispbbs.asp?boardid=23&id=358816