我认为正确的方法是

I think the right way to go is

foreach (GridviewRow row in gvFormula.Rows)
{
    //should you have a TextBox called txt1
    ((TextBox)row.FindControl("txt1")).ReadOnly = true;
    //or if you need invisible
    ((TextBox)row.FindControl("txt1")).Visible = false;
    
    //and so on and so on...
}

如果需要，你也可以在RowDataBound事件上使用

You can also use it on RowDataBound event if you need