Once the economy and social usefulness of the motor car was demonstrated and with its superiority being proved, most of the early hostility to it in rural regions disappeared.
B. and its superiority to the horse had been proved
C. and its superiority to the horse
这个题不是很理解, 选项B 是正确答案但是在选项C 里不可以把its看成前面的 the economy and social usefulness吗? 那样的话就省略掉前面的BE 动词, 这样做为什么不可以呢? 很是不理解, 请大家帮忙。