一个虚拟语气倒装的语法问题

题目

一个虚拟语气倒装的语法问题
Should you experience any difficult ,do not hesitate to contact
one of my staff members.为什么第一个用的是Should

答案

Should you experience any difficult,do not hesitate to contact one of my staff members.
一、句子使用语气的解释：
这是个“虚拟条件句 + 祈使句”的复合句
1.条件虚拟语气在这里是一种客套语,即不强求对方非得接受 .
2.祈使句也是一种客气,表示请求
二、关于条件虚拟的倒装：
条件虚拟句常可以用倒装语序表示.倒装时只要省去 if 再把助动词或情态动词提前放在主语前即可,如本句：
提前 should：Should you experience any difficult = If you should experience any difficult,假如你们觉得有什么难题的话,
再如：
* 提前 were：Were you to be here tomorrow,...= if you were to be here tomorrow,...假如你明天会在这里的话,...
* 提前 did：Did he come now,...= If he came now,...如果他现在就来的话,...
* 提前 had：Had the students finished their homework on time,...= If the students had finished their homework on time,...如果学生原来就按时完成了作业的话,...