it has four windows.此句中it是主语,has是谓语,four windows是宾语.
my name is zhao gang.my name是主语,is是谓语,zhao gang是表语.
I sit behindn li lei.i是主语,sit是谓语,behindn li lei是地点状语
I thank him very much.i是主语,thank是谓语,him是宾语,very much是状语,修饰动词thank