C#如何使用DateTime.Now.AddDays方法获取任一天的信息

public DateTime AddDays(double value)
参数说明
Value：双精度Double值，由整数和小数部分组成的天数。
DateTime：返回DateTime对象，它的值是此DateTime对象所表示的日期和时间与value所表示的天数之和。

//使用DateTime.Now.AddDays方法获取任一天的信息
namespace _060
{
    public partial class Form1 : Form
    {
        private Button? button1;
        public Form1()
        {
            InitializeComponent();
            Load += Form1_Load;
        }
        private void Form1_Load(object? sender, EventArgs e)
        {
            // 
            // button1
            //
            button1 = new Button
            {
                Location = new Point(106, 34),
                Name = "button1",
                Size = new Size(90, 23),
                TabIndex = 0,
                Text = "获取",
                UseVisualStyleBackColor = true
            };
            button1.Click += Button1_Click;
            // 
            // Form1
            // 
            AutoScaleDimensions = new SizeF(7F, 17F);
            AutoScaleMode = AutoScaleMode.Font;
            ClientSize = new Size(284, 81);
            Controls.Add(button1);
            Name = "Form1";
            StartPosition = FormStartPosition.CenterScreen;
            Text = "获取昨天信息";            
        }
        private void Button1_Click(object? sender, EventArgs e)
        {
            MessageBox.Show(
              "昨天是：" + DateTime.Now.AddDays(-1).ToString("yyyy年M月d日") + Environment.NewLine +    //昨天
               "前天是：" + DateTime.Now.AddDays(-2).ToString("yyyy年M月d日") + Environment.NewLine +  //前天
               "明天是：" + DateTime.Now.AddDays(1).ToString("yyyy年M月d日") + Environment.NewLine +    //明天
               "后天是：" + DateTime.Now.AddDays(2).ToString("yyyy年M月d日") + Environment.NewLine +   //后天
               "提示！");
        }
    }
}