List<Subscription> subscription = new List<Subscription>
{
    new Subscription{ Type = "Trial",Type = "Offline",Period = 30  },new Subscription{ Type = "Free",Period = 90  },new Subscription{ Type = "Paid",Type = "Online",Period = 365 }
};

现在我想使用LINQ在这个列表中再添加一个项目.我该怎么做？