Question

___ it rain tomorrow,we would have to put off the meeting.

Answer 1

should it rain tomorrow,we would have to put off the meeting.

if it should rain tomorrow,we would have to put off the meeting.

应为Were it to rain tomorrow,we would have to put off the meeting.

况且rain为动词.答案错误.

虚拟语气倒装 仅should were had 提前,其他不动.were to 与should等效用于对将来的虚拟.were,had分别表对现在、过去的虚拟.具体见虚拟语气用法及虚拟语气倒装.