is not.
他的口语讲的很好,好象他是他是一个英国人并且在那边住了几年,但是事实上他不是.
as if从句用had been型虚拟形式：表示从句的动作先与主句的动作发生.例如：He looks as if he had been ill.
以as if引导的从句如果不是表示虚拟,而是表示可能的事实,则从句中的谓语动词要用陈述语气.
例如：He spoke English well as if he had been an Englishman and would have lived for serval years in Britain .Actually,he was.
was跟 spoke保持一致
这两题要注意区别哦.