You work as an ASP.NET Web Application Developer for SomeCompany. The company uses Visual Studio .NET 2010 as its application development platform.  You are creating an ASP.NET Web application using .NET Framework 4.0.  The application holds a Web page named MyHome.aspx.  You are creating a button with a rolloverimage on MyHome.aspx. However， when mouse hovered over the button image， the rolloverimage is retrieved from the server in a separate request. You need to use an improved rollover button in which the button„s rolloverimage is already downloaded and stored in the browser’s cache， as a result when you hover over the button， it is instantly displayed. What will you do to accomplish this？（）