What would have happened , as far as the river bank?
A. Bob had walked farther
B. if Bob should walk farther
C. had Bob walked farther
D. if Bob walked farther
网友回答
A. Bob had walked farther
B. if Bob should walk farther
(答案→)C. had Bob walked farther
D. if Bob walked farther
解析：考查虚拟语气。根据句意可知考查与过去事实相反的虚拟语气，故从句用had + v-ed，had Bob walked farther = if Bob had walked farther，选C。