问题补充:
a little earlier, you could have caught the last bus.
A. If you would arrive
B. If you arrived
C. Should you arrive
D. Had you arrived
答案:
A. If you would arrive
B. If you arrived
C. Should you arrive
(答案→)D. Had you arrived
解析:句意:如果你早一些到达,你就可能赶上最后一班车了。从you could have caught the last bus.可知前面是和过去相反的虚拟条件句,If you had arrived a little earlier,这时可以省略if,提前had,所以选D。