题目: 

In 1921，the southern part of Ireland became independent and the Republic of Ireland was founded. It is a state （    ）covers  70，000 square kilometers， or five-sixths of the island of Ireland.  

问题: 

1.括号的答案给的是which/that,请问老师括号前的it是什么成分？which/that在这又引导的是什么从句? 

2.在这可以理解成强调句吗？强调句修饰人的时候能用who引导强调成分，那强调物的时候可以用which吗？强调句的that即可指人也可指物吗？