反正你就记住,时态倒退一格.与过去事实相反,后面跟过去完成时,had+过去分词
与现在事实相反,后面跟一般过去时.
与将来事实相反,后面跟一般过去时或should + 动词原形
If only I were a boy.= I wish I were a boy.
我要是个男孩就好了(说话人是女孩,和现在事实相反)
If only I had not come home alone.
要是我不是一个人回的家就好了.(说话人是一个人回的家,但发生了不好的事情,和过去事实相反)
If only I could see you tomorrow.要是我明天能见到你就好了.(能见到你的可能性很小,和将来事实相反)