thE EDitor At onCE sEnt thE journAlism A FAx in...

in which是带介词的 关系代词 引导定语从句 修饰a fax并作定语从句中的状语 在定从中的意思 也就是in the fax

which引导的定语从句，which 在句中代指fax,editor 是在fax中的，所以有个从属关系，这里用介词in表示从属关系，he informed the editor in the fax

in the fax，一般是紧跟着的那个名词。顺过来就是 He had at last been allowed to send a fax. In the fax he informed the editor that he had been...

问题1，in which 引导一个定语从句，来说明传真的内容，因为内容是in the fax的，所以要用in which。 问题2，he had at last been allowed to send a fax是句子主干，in which 是定性定于从句修饰fax；which surrounded the president's palace...