// 打开Folder操作

            var openFolderTableElement =

               driver.FindElement(

               By.CssSelector("table[data-name='图片']"));

            var mouseOverAction = new OpenQA.Selenium.Interactions.Actions(driver);

            mouseOverAction.MoveToElement(openFolderTableElement);

            //notice： Actions必须要执行perform

            mouseOverAction.Perform();

            openFolderTableElement.FindElement(By.CssSelector("div.menuBtn a.option_Open")).Click();