高中英语定语从句做语法填空HequicklypickedupthetelephoneandpretendedtobeverybusyansweringanimportantcallfromsomeoneinNewYork（）wantedtobuyabigandexpensivehouseinthecountry.括号里答案是:who所填

　　高中英语定语从句

　　做语法填空HequicklypickedupthetelephoneandpretendedtobeverybusyansweringanimportantcallfromsomeoneinNewYork（）wantedtobuyabigandexpensivehouseinthecountry.括号里答案是:who所填词引导定语从句修饰先行词someome.并在定语从句中作主语,故用who.我填that请请问someone不是不定代词吗不是只能用that?况且That也是可以做主语啊…求高手解答!Thanks!