1.Since December,when the report came out,the mayor,neighborhood activists and various parent-teacher associations have engaged in a fierce battle over its validity:over the guilt of the steel-casting factory on the western edge of town,over union jobs versus children's health and over what,if anying,ought to be done.

 

分析：主干：...the mayor,...associations have engaged in a... battle(over...)

 

①谓语用了现在完成时，与句首since引导的时间状语搭配。when引导非限制性定语从句，修饰December（注意，不是时间状语从句）。②句子的主语是一个名词词组，含三个中心名词（mayor,activists,associations)。validity是“有效性，正确性”，冒号后的内容（三个并列的over...短语）进一步做了详细的说明，可以把冒号后的内容看做是over its validity的同位成分。

 

译文：自从12月份报告发布以来，市长，社区活跃分子和各家长教师协会就这份报告的正确性进行了激烈的争论；争论城市西郊铸钢工厂是否有责任，争论工会保护职工工作与儿童的健康之间的矛盾，争论应该采取什么样的措施（如果要采取措施的话）。

 

2.But Nature is indifferent to human notions of fairness,and a report by the Fish and Wildlife Service showed a worrisome drop in the populations of several species of North Atlantic sea turtles,notably loggerheads,which can grow to as much as 400 pounds.

 

分析：主干：...Nature is indifferent to human notions...and a report...showed a(worrisome)drop(in...)

 

①and并列连接两个分句。后一个分句中，介词短语by...作a report的后置定语，表示该报告的来源；介词短语in...作宾语a drop的后置定语。②这里有好几个介词短语，分别修饰其前面的名词。两个逗号间的notably loggerheads作turtles的同位语，后面有一个非限制性定语从句对这种海龟做进一步解释和说明。

 

译文：不过大自然一点都不会在乎人类所谓公平的想法。渔业和野生动物署的一个报道表明，几种北大西洋海龟的数量急剧下降，令人担忧，尤其是能够生长到400磅重的灵龟。