虚拟语气中,提前WERE,HAD,SHOULD问题

虚拟语气中,提前WERE,HAD,SHOULD问题
这是虚拟语气中省略的一种用法 有时可以把含有助动词、情态动词、be或have的虚拟条件句中的连词if 省去,而将had ,should,were 等词提到主语之前,即用倒装结构,这时候,如果出现not等否定词,否定词需放在主语后面.我要问的是“如果出现not等否定词,否定词需放在主语后面.”怎么理解,麻烦请给出列句

as if 的用法
as if 好像,好似 She spoke to me as if she knew me. 她和我说话的神情,好像她早就认识我似的. (= as though)
as if 的用法
一、as if 从句的作用 1. 在look, seem 等系动词后引导表语从句.如: She looks as if she were ten years younger. 她看起来好像年轻了十岁. It seems as if our team is going to win. 看来我们队要胜了. 2. 引导方式状语从句.如: She loves the boy as if she were his mother. 她爱这男孩,就好像她是他的母亲一样. The child talked to us as if he were a grownup. 那孩子跟我们谈起话来,像个成年人似的. 二、as if 还可用于省略句中 如果as if 引导的从句是“主语+系动词”结构,可省略主语和系动词,这样as if 后就只剩下名词、不定式、形容词(短语)、介词短语或分词.如: He acts as if (he was) a fool. 他做事像个傻子. Tom raised his hands as if (he was going) to say something. 汤姆举起手好像要说什么. She left the room hurriedly as if (she was)angry. 她匆忙离开房间好像生气的样子. 三、as if 从句的语气及时态 1. as if 从句用陈述语气的情况. 当说话者认为句子所述的是真实的或极有可能发生或存在的事实时.如: It sounds as if it is raining. 听起来像是在下雨. He talks as if he is drunk. 从他谈话的样子来看他是醉了. 2. as if 从句用虚拟语气的情况. 当说话人认为句子所述的是不真实的或极少有可能发生或存在的情况时.从句虚拟语气动词时态的形式如下: (1)如果从句表示与现在事实相反,谓语动词用一般过去时.如: You look as if you didn’ t care. 你看上去好像并不在乎. He talks as if he knew where she was. 他说话的样子,好像他知道她在哪里似的. (2)从句表示与过去事实相反,谓语动词用“had+过去分词”.如: He talks about Rome as if he had been there before. 他说起罗马来好像他以前去过罗马似的. The girl listened as if she had been turned to stone. 那女孩倾听着,一动也不动,像已经变成了石头似的. (3)从句表示与将来事实相反,谓语动词用“would/could/might+动词原形”.如: He opened his mouth as if he would say something. 他张开嘴好像要说什么. It looks as if it might snow. 看来好像要下雪了.
(4)as if 后面可以接陈述语气和虚拟语气,如果句子的情况是真实的,那么只要保持时态一致即可,如果后面接的并非真实情况,则要按照虚拟语气规则把句子形式改变(简单说就是事态倒退原则). 举例: it seems as if it is raining.外面看起来象是下雨了.(陈述) it seems as it it was raining.外面看起来好像下雨一样.(虚拟,其实并没有下雨)