Would you like to go out with me?

　　go out with 和...约会、交往

　　你可以这样回答：

　　I'm sorry. I've got a boyfriend/girlfriend. 不好意思，我已经有男友了。

　　I thought you'd never ask. 终于等到你这句话！

　　Sorry, I have other plans. 抱歉，我已经有约了。

　　你也可以问：

　　Are you seeing anyone?

　　对方可能能会回答

　　I'm already seeing somebody. 对不起我已经有约会对象了。