https://www.cnblogs.com/shanfeng1000/p/13402152.html
//Task关闭
CancellationTokenSource cancel = new CancellationTokenSource();
if (符合开启异步Task){
var task = Task.Run(async delegate
{
//倒计时5秒后,执行Method方法
await Task.Delay(5000,cancel.Token);
Method();
});
}