我这里有个小问题，我需要一点帮助。

我想是因为switch语句，但我不知道具体在哪里。

但微软Visual Studio2015强调了一些事情。

例如:

（位于第24行）

（位于第29行）

上面说:

类型“bool”无法隐式转换为“string”。

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Hello_World
{
    class Program
    {
        static void Main(string[] args)
        {
            string random = string.Empty;
            string input = string.Empty;
            string choice = string.Empty;

            // Ask something
            do
            {
                Console.Clear();
                Console.WriteLine("World is a Savage Machine, whatever you ask, it'll give you a nasty answer.");
                Console.WriteLine("This is more a Joke, don't be sad if your Question isn't answered ;D");
                Console.Write("\nAsk World something: ");
                string input = Console.ReadLine();
            } while (input == "");

            switch (choice)
            {
                case input.StartsWith("Who"):
                    Console.WriteLine("Question: Who cares?");
                    break;

                case input.StartsWith("How"):
                    Console.WriteLine("Kys. That's how.");
                    break;

                case input.StartsWith("Where"):
                    Console.WriteLine("How does this make sense?");
                    break;

                case input.StartsWith("If"):
                    Console.WriteLine("If somebody would care, that'd be intresting.");
                    break;

                case input.StartsWith("When"):
                    Console.WriteLine("When the Dinasours were young");
                    break;

                case input.StartsWith("What"):
                    Console.WriteLine("What is the Purpose of this Question?");
                    break;

                default:
                    Console.Write("Not availible right now... we're working on it ;D");
                    break;

            }


            random = ("Das ist falsch.");

            // Antwort
            Console.Clear();
            Console.WriteLine("The Answer to {0} is: {1}", input, random);
            Console.ReadKey();


            // Beenden
            do
            {
                     Console.Write("Press <Enter> to exit... ");
                     while (Console.ReadKey().Key != ConsoleKey.Enter) { }
            } while (true);
        }
    }
}