一道英语语法单选的问题

你问的是关于 虚拟语气中if的省略 的问题。

虚拟条件句中有were, had, should时, 可把if省略,而把were, had, should
放在主语前,用倒装结构, 这种结构主要用于书面语中．
如：
1．Were it necessary, I might resign．＝If it were necessary, I might resign．
2．Had you informed me earlier, I would not have signed the contract．
＝If you had informed me earlier, I would not have signed the contract．
3．Should I have time, I would call on her．＝If I should have time, I would call on her．
4．Should it rain tomorrow, we would have to put off the visit to the Summer Palace．
＝If it should rain tomorrow, we would have to put off the visit to the Summer Palace．
5．Should I meet her, I would tell her．= If I should meet her, I would tell her．
6．Were I in your position , I would do it better．= If I were in your position, I would do it better．
7．Were he to tell us everything, we could try to solve his problem．
8．There is a real possibility that these animals could be fright ened, should there be a