29. 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 (E) with its superiority to the horse having been 这道题在白勇语法全解的128页也出现过,两次我都做错了。我选了C,答案是B,一直想不明白,请nn帮忙解释一下。 once从句前半段是一般过去时,为什么这里可以用过去完成时?3x |