where
如这句,where是可以引导非限制性定语从句的:
They set up a state for their own , where they would be free to keep Negroes as slaves。
关系副词when和where的先行词是表示时间(如the day, the days, the time, the year等)和地点(如the place, the house, the factory, the station等)的一类词,而关系副词why的先行词通常只是the reason(s)。另外,when和where可引导限制性和非限制性定语从句,而why则只用于引导限制性定语从句,不用于引导非限制性定语从句。
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再者,beijing在定语从句里充当什么成分呢?应该是充当状语才对的,where=in which,即We spent the Spring Festival in Beijing last year.
如果只用which就成了:
We spent the Spring Festival Beijing last year.===>spent后面成了双宾语了,语法上可以,逻辑上说不通,因为Beijing不是春节。
参考资料:http://www.hjenglish.com/subject/gaokao/page/37921/