英语翻译
Since the sea covers the greater part of the earth's surface,it is quite reasonable to regard the sea floor as the basic form of the crust of the earth,with,superimposed upon,it the continents,together with the islands and other features of the oceans.
参考译文：既然海洋覆盖着地球的大部分表面,因此完全有理由把海床看作地壳的基本模壳,上面附加着大陆以及岛屿和海洋的其他形态.
with,superimposed upon,it the continents,together with the islands and other features of the oceans.1.with后为啥加个逗号 这样是?2.superimposed upon又是个逗号?3.it the continents 如果去掉这个it反倒好理解 或者去掉the 这个it the continents有这种用法么.