c# 如何把两组汉字随机排序打乱生成一组标题

例如：

一组为：一，二三，四五六，七，九十。

另一组：你好，他好，塔塔，你好，拜拜，再见。

然后组合成指定长度。

如：

一你好塔塔二三你好

拜拜七他好四五六一

再见他好四五六九十

这种应该用什么方法实现？蒙圈中，小白一枚，求大神指点。

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace Q753166
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string[] grp1 = textBox1.Text.Split('，');
            string[] grp2 = textBox2.Text.Split('，');
            string rnd = "";
            while (true)
            {
                rnd += grp1.Union(grp2).OrderBy(x => Guid.NewGuid()).First();
                if (rnd.Length > int.Parse(textBox3.Text)) rnd = "";
                if (rnd.Length == int.Parse(textBox3.Text)) break;
            }
            listBox1.Items.Add(rnd);
        }
    }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace Q753166
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string[] grp1 = textBox1.Text.Split('，');
            string[] grp2 = textBox2.Text.Split('，');
            string rnd = "";
            while (true)
            {
                var grp = grp1.OrderBy(x => Guid.NewGuid()).Take(2).Concat(grp2.OrderBy(x => Guid.NewGuid()).Take(2));
                rnd = string.Join("", grp.OrderBy(x => Guid.NewGuid()));
                if (rnd.Length == int.Parse(textBox3.Text)) break;
            }
            listBox1.Items.Add(rnd);
        }
    }
}

namespace Q753166
{
    partial class Form1
    {
        /// <summary>
        /// Required designer variable.
        /// </summary>
        private System.ComponentModel.IContainer components = null;

        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        /// <param name="disposing">true if managed resources should be disposed; otherwise, false.</param>
        protected override void Dispose(bool disposing)
        {
            if (disposing && (components != null))
            {
                components.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Windows Form Designer generated code

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.textBox1 = new System.Windows.Forms.TextBox();
            this.textBox2 = new System.Windows.Forms.TextBox();
            this.label1 = new System.Windows.Forms.Label();
            this.textBox3 = new System.Windows.Forms.TextBox();
            this.button1 = new System.Windows.Forms.Button();
            this.listBox1 = new System.Windows.Forms.ListBox();
            this.SuspendLayout();
            // 
            // textBox1
            // 
            this.textBox1.Location = new System.Drawing.Point(12, 12);
            this.textBox1.Name = "textBox1";
            this.textBox1.Size = new System.Drawing.Size(259, 20);
            this.textBox1.TabIndex = 0;
            this.textBox1.Text = "一，二三，四五六，七，九十";
            // 
            // textBox2
            // 
            this.textBox2.Location = new System.Drawing.Point(12, 38);
            this.textBox2.Name = "textBox2";
            this.textBox2.Size = new System.Drawing.Size(259, 20);
            this.textBox2.TabIndex = 1;
            this.textBox2.Text = "你好，他好，塔塔，你好，拜拜，再见";
            // 
            // label1
            // 
            this.label1.AutoSize = true;
            this.label1.Location = new System.Drawing.Point(9, 67);
            this.label1.Name = "label1";
            this.label1.Size = new System.Drawing.Size(34, 13);
            this.label1.TabIndex = 2;
            this.label1.Text = " 长度";
            // 
            // textBox3
            // 
            this.textBox3.Location = new System.Drawing.Point(53, 64);
            this.textBox3.Name = "textBox3";
            this.textBox3.Size = new System.Drawing.Size(218, 20);
            this.textBox3.TabIndex = 3;
            this.textBox3.Text = "9";
            // 
            // button1
            // 
            this.button1.Location = new System.Drawing.Point(12, 90);
            this.button1.Name = "button1";
            this.button1.Size = new System.Drawing.Size(79, 24);
            this.button1.TabIndex = 4;
            this.button1.Text = "生成";
            this.button1.UseVisualStyleBackColor = true;
            this.button1.Click += new System.EventHandler(this.button1_Click);
            // 
            // listBox1
            // 
            this.listBox1.FormattingEnabled = true;
            this.listBox1.Location = new System.Drawing.Point(12, 120);
            this.listBox1.Name = "listBox1";
            this.listBox1.Size = new System.Drawing.Size(259, 355);
            this.listBox1.TabIndex = 5;
            // 
            // Form1
            // 
            this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
            this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
            this.ClientSize = new System.Drawing.Size(283, 486);
            this.Controls.Add(this.listBox1);
            this.Controls.Add(this.button1);
            this.Controls.Add(this.textBox3);
            this.Controls.Add(this.label1);
            this.Controls.Add(this.textBox2);
            this.Controls.Add(this.textBox1);
            this.Name = "Form1";
            this.Text = "Form1";
            this.ResumeLayout(false);
            this.PerformLayout();

        }

        #endregion

        private System.Windows.Forms.TextBox textBox1;
        private System.Windows.Forms.TextBox textBox2;
        private System.Windows.Forms.Label label1;
        private System.Windows.Forms.TextBox textBox3;
        private System.Windows.Forms.Button button1;
        private System.Windows.Forms.ListBox listBox1;
    }
}