虚拟语气should/were和陈述语气shall/is用的意思差别？

请教曹老师：

“That is what Mr. Hilton Cubitt, of Riding Thorpe Manor, Norfolk, is very anxious to know.

This little conundrum came by the first post, and he was to follow by the next train.

There’s a ring at the bell, Watson. I should not be very much surprised if this were he.”

这正是希尔顿·丘比特先生急着想搞了解的问题，他住在诺福克郡赖丁索普庄园。

这个小谜团是今天首班邮车送来的，他本人筹备搭乘下一班火车前来。

门铃响了，华生。来人若是他，我一点也不会感到吃惊。”

节选福尔摩斯《The Adventure of the Dancing Man》。



剖析这一句： I should not be very much surprised if this were he.

这里为何要用虚拟语气should, were? 假如用陈述句

I SHALL not be very much surprised if this IS he. 意义有什么不同？

虚拟语气反映了说话的人的心理想法，故事中，是福尔摩斯当时说的。

我就说想请教老师：

福尔摩斯说 I SHOULD not be very much surprised if this WERE he.

和假如福尔摩斯如此说：

I SHALL not be very much surprised if this IS he.

那样，对于福尔摩斯，这二种说法，内心想法到底有什么不同？




福尔摩斯判断Mr. Hilton Cubitt会来找他。但此人什么时间来，他不确定。所以他说： I should not be very much surprised if this were he. 字面的意思是（虽然来人是他的可能性不大，但）：假如来的人是他，我不会非常惊讶的。这其实等于在说：Ishall be very much surprised if this is nothe. 假如来的人不是他，我会很惊讶的。英国绅士说话绕弯子。