请将下面的程序补充完整,使得程序输出“飘是的书”。 include using namespace std class Book{ public: Book(char*str)|strcpy(title,str); ______void Printlnfo(){cout<<title<<endl;} protected: char title[50]; }; class MyBook:public Book{ public: MyBook(char*s1,char*S2=“”): ______strcpy(owner,s2);} virtual void PrintInfo(){cout<<title<<“是”<<owner<<“的书”<<endl;} private: charowner[10]; }; int main(){ Book*ptr=new MyBook(“飘”); ptr->Printlnfo(); return 0; }