sr.BaseStream.Seek(0, SeekOrigin.Begin);这一句是什意思，请仔细讲解

sr是什么 应该是某个类的对象吧，看样子是IO包的某个对象

public void ReadFile()//文本
{

FileStream fs = new FileStream("d:\\MyFile.txt", FileMode.Open, FileAccess.Read,FileShare.Read);
StreamReader sr = new StreamReader(fs);
sr.BaseStream.Seek(0, SeekOrigin.Begin);
string str = sr.ReadLine();
while (str != null)
{
Console.WriteLine(str);
str = sr.ReadLine();
}
sr.Close();
fs.Close();

Seek是一个定位的函数，看看msdn吧