数组并不满足OO的替换……（同样的东西还有struct等）
代码语言：js复制
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
Son[] sons = new Son[5];
Father[] fathers = sons;
TestMethod(fathers);
}
private void TestMethod(Father[] ff)
{
ff[0] = new Daughter();//Here throw a exception.
}
private class Father { }
private class Daughter : Father { }
private class Son : Father { }
