C# 派生无无参构造构造方法的父类

using System;
using System.Collections.Generic;
using System.Text;

namespace DailyCoding.Code
{
    // 父类无无参构造方法
    public class _20210424_1
    {
        public void Run()
        {
            var r = new _20210424_1_C();
        }
    }

    public class _20210424_1_P
    {
        public string _x;

        public _20210424_1_P(string x) => _x = x;
    }

    public class _20210424_1_C : _20210424_1_P
    {
        public _20210424_1_C()
            : base("默认构造函数")

        {

        }
    }
}