大全T551

大全上答案是C，但白勇说是B,其理由是“C选项and连接once从句和名词短语its superiority ，两者形式不对称”。但b选项的时间had been又怎么解释呢？ 谢谢。

1.        Once the economic and social usefulness of the motor car was demonstrated and with its superiority to the horse being proved, much of the early hostility to it in rural regions disappeared.

(A) and with its superiority to the horse being

(B) and its superiority over the horse had been

(C) and its superiority to the horse

(D) its superiority over the horse（C）

(E) with its superiority to the horse having been