想问问"...,done..."结构存在吗?请看两到题~~~~

The Anasazi settlements at Chaco
            Canyon were built on a spectacular scale with more than 75 carefully engineered structures, of up to 600 rooms each, were connected by a complex regional system of roads.

(A) with more than 75 carefully engineered structures, of up to 600 rooms each, were

(B) with more than 75 carefully engineered structures, of up to 600 rooms each,

(C) of more than 75 carefully engineered structures of up to 600 rooms, each that had been

(D) of more than 75 carefully engineered structures of up to 600 rooms and with each

(E) of more than 75 carefully engineered structures of up to 600 rooms each had been

红色为正确答案~~~

(A) propagated by seeds, either sown directly in the field or in plant beds designed for producing

(B) propagated by seeds, sown either directly in the field or sown in plant beds designed so as to produce

(C) is propagated by seeds either sown directly in the field or in plant beds designed so that they produce

(D) is propagated by seeds sown either directly in the field or in plant beds designed to produce

(E) is propagated by seeds, sown either directly in the field or sown in plant beds designed for producing  

这两个题都涉及到一个我不解的问题,正如第1题的B和第2题的E,逗号后面的分句都是done引导的,,,能否看成是省略了"which is/are"的结构呢?......或者还有什么比较可听的解释?

尤其是第1题,,,我觉得选了B后,简直都翻译不出来它想说什么了...请大侠们指点...

Thanks!