新概念英语4 Lesson 30,一句话,其中标点符号的解释.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.这句话with后面是逗号,upon后面又是逗号,并且it the continents,不理解,为何不直接写为：with superimposed upon it,together with……,所以这句话的标点符号,

新概念英语4 Lesson 30,一句话,其中标点符号的解释.
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.
这句话with后面是逗号,upon后面又是逗号,并且it the continents,不理解,为何不直接写为：with superimposed upon it,together with……,所以这句话的标点符号,