题目内容：

＿,we shall go on a picnic
这里为何一定要用 should the weather be fine 不能用 were the weather to be fine

优质解答

关键词在于【shall】.表示“未来”的虚拟语气,所以必须用should.例子：Should the weather be bad,we shall/will have to move the meeting to another date.“were”代表的是“过去”的虚拟语气,如果要用were的话,...