jacky
1.用as引导非限制性定语从句的：
Asweallknow；Aseveryone/everybodyknows；
Asisknownto妒部北正探措重usall；Asisknowntoeveryone/everybody
2.用It做形式主语，that从句做真正主语的：
Itisknownt计没沙血权率品源范战空ousallthat从句；
Itisknowntoev呢高村eryone/everybo住父却乐职你袁间甲七效dythat从句
3.用what引导主语从句的，后用that引导表语从句的：
Whatisknowntousallisthat从句；
Whatiskno跟查投火政念盾那就想代wntoeveryone/everybodyisthat从句
