1)major key,主关键词2)primary key,主关键词3)main key stratum,主关键层4)primary key,主关键字5)host relationship,寄主关系6)suzerainty,宗主关系7)relation between the leaders and the staff members,宾主关系8)Democratic Solicitude,民主关怀9)autonomous tariff,自主关税10)primary relation,主关系
用法和例句
Because the coal caving height is larger in fully mechanized top coal caving mining,thick and hard rock strata at higher position turn into the main key stratum,which have large movement and higher impact energy.
