it is impossible that the criminal was arrested last nightit is the criminal that stole the necklace last sunday who was arrested by the police这两句是什么句强调句还是主语从句?为什么

it is impossible that the criminal was arrested last nightit is the criminal that stole the necklace last sunday who was arrested by the police这两句是什么句强调句还是主语从句?为什么
it is impossible that the criminal was arrested last night
it is the criminal that stole the necklace last sunday who was arrested by the police
这两句是什么句强调句还是主语从句?为什么

it is impossible that the criminal was arrested last nightit is the criminal that stole the necklace last sunday who was arrested by the police这两句是什么句强调句还是主语从句?为什么
第一句是主语从句,第二句是强调句.因为把it is that删去后,第一句读不通,第二句可以

第一句 是It is adj ……的句型
第二句是强调句 It is …… who 此句中的that是修饰criminal