求专业英语阅读教程的期考题！谢谢！

Cascading Style Sheets (CSS)
A style sheet mechanism that has been specifically developed for Web page designers and users .Style sheets describe how documents are presented on screens ,in print ,and even in spoken voice. Style sheets allow the user to change the appearance of hundreds of Web pages by changing just one file .A style sheet is made up of rules that tell a browser how to present a document .Numerous properties may be defined for an element ;each property is given a value.