问题
选择题
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
答案
答案：C
考查虚拟语气。根据语境为过去事实相反的虚拟语气，故用had Bob walked farther，等于if Bob had walked farther，选C。