After the party,__they picked up the rubbish on the floor.A.that has been dropped
问题描述：
After the party,__they picked up the rubbish on the floor.A.that has been dropped
B.which had been droppen C.that had been fallen.选什么为什么
答
C
横线应该在rubbish之后吧?
A错在has,因为主句是一般过去时（picked）,而定语从句的动作应在主句谓语动词之前就已经发生了.所以应该用过去完成时had dropped.
B项错在droppen,没有这种过去分词.
C项错在fallen.fall是不及物动词,没有被动语态.不好意思B选项打错了，应该是dropped 那应该是选B 了吧？对。