----------C# & C++------
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Windows.Forms;
using System.Reflection;
using System.ComponentModel;
using System.Data;
using System.Linq;
using System.Text;
using MySql.Data.MySqlClient;
using System.IO;
using System.Threading;

-------VB.NET-------------

Imports System 

----------Swift----------------

import UIKit

----------php-----------

namespace Foo\Bar;
include 'file1.php';