C :

#include<stdio.h>
int main()
{
	printf("Hello World!\n");
	printf("I'm a C++ program.\n");
}

C++ :

#include<iostream>

using namespace std;
int main()
{
  cout<<"Hello World!"<<endl<<"I'm a C++ program.";
  //system("pause");
  return 0;
   


}

Pascal :

begin
writeln('Hello World!');
writeln('I''m a C++ program.')
end.