是后置定语修饰 a burst of activity 指的是, 一系列过程/步骤。 这是修饰laying of submarine cables, 你想想看, 假如你要在海底拉线, 一定有很多步骤。这是倒装句, 我把它按循序不改变意思重写一下, 你就懂了the gentle slope of the continental shelf, geologically part of the continent(这个短语是修饰前面的,指明它是大陆的一部分), runs from the shore line out to distance which may be anywhere from a few miles to a few handre...