public async Task AsyncMethod1()
{
    HttpClient client = new HttpClient();
    await client.GetAsync("https://www.baidu.com/");
}

public async Task<byte[]> AsyncMethod2()
{
    WebClient client = new WebClient();
    return await client.UploadFileTaskAsync("", "");
}

public void TaskMethod()
{
    //Task.Run
    Task.Run(() =>
    {

    });

    Task.Run(async () =>
    {
        await AsyncMethod1();
    });

    //Start
    Task t = new Task(Method1);
    t.Start();

    //Task.Factory.StartNew  创建并启动
    t = Task.Factory.StartNew(Method1);

    Task t1=new Task(Method1), t2 = new Task(Method1), t3 = new Task(Method1);
    Task[] tasks = new Task[] { t1, t2, t3 };
    //等待所有完成
    Task.WaitAll(tasks);
    //等待任意一个完成
    Task.WhenAll(tasks);

    //任务t完成后，调用Method2
    t.ContinueWith(Method2);
}

public void Method1()
{

}

public void Method2(Task t)
{
    Console.WriteLine($"task {t.Id} finished");
}