In a country that defines itself by ideals, not by shared blood, who should be allowed to come, work and live here? (06.6 Passage 2)
分析主干：who should be allowed to...
1.句子主干部分是一个特殊疑问句，用了被动语态。三个不定式短语to come,work and live here 作主语的补足语。2.句首表示地点的介词短语In a country 在句中作地点状语，后面的that 引导定语从句修饰a country，by... not by...是并列结构，表示“由......而不是由......(决定)”。