Англо-русский словарь и ошибка: Невозможно преобразовать группу методов "ReadLine" - C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.IO;
using System.Text;
using System.Windows.Forms;
 
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        StreamReader rs1;
        StreamReader rs2;
        string[] rus_words;
        string[] eng_words;
        public static string ReadLine();

        public Form1()
        {
            InitializeComponent();
        }
 
        private void button2_Click(object sender, EventArgs e)
        {
            Application.Exit();
        }
 
        private void Form1_Load(object sender, EventArgs e)
        {
            rs1 = File.OpenText ("rus_text.txt");
            rs2 = File.OpenText ("eng_text.txt");
            rus_words = new string[20];
            eng_words = new string[20];
 
            int  @i;
            while (!rs1.EndOfStream)
            {
 
            rus_words[i] = rs1.ReadLine;
            eng_words[i] = rs2.ReadLine;
            listBox1.Items.Add(eng_words);
            i++;
 
            }
 
            rs1.Close();
            rs2.Close();

        }
 
        private void button1_Click(object sender, EventArgs e)
        {
 
            StreamWriter rs2;
            rs2 = File.AppendText("ex.txt");
            string s = textBox1.Text;
            rs2.WriteLine(s, Encoding.Unicode);
            rs2.Close();
        }
    }
}