"Why, Dr. Watson, that's not you, is it? You are the last man that I should have expected to see out on the moor at this time of night. But, dear me, what's this? Somebody hurt? Not 

- don't tell me that it is our friend Sir Henry!" He hurried past me and stooped over the dead man. I heard a sharp intake of his breath and the cigar fell from his fingers.

在这一句中， You are the last man that I should have expected to see out on the moor at this time of night.

这里为什么用了情态动词+完成时？？？should have expected 是虚拟呢，还是表可能性推测用法？另外，这里的should是否可用would替换？ 麻烦老师多分析一下这里使用should have expected的意义。谢谢！