要注意空格、换行和符号，用 C++ 代码解答：

main(){__builtin_puts("Hello World!\nI'm a C++ program.");}

#include <iostream> using namespace std; int main(){ cout<<"Hello World!"<<endl<<"I'm a C++ program."; }

#include<bits/stdc++.h> using namespace std; int main(){ cout<<"Hello World!"<<endl; cout<<"I'm a C++ program."<<endl; return 0; }