Originally introduced by Netscape Communications, (1) are a general mechanism which HTTP Server side applications, such as CGI (2) , can use to both store and retrieve information on the HTTP (2) side of the connection. Basically, Cookies can be used to compensate for the (4) nature of HTTP. The addition of a simple, persistent, client-side state significantly extends the capabilities of WWW-based (5) .

5（）

A.graphics

B.processes

C.scripts

D.texts

如图所示，一根粗细均匀的木棒放在盛有半碗水的碗中，此时的木棒可以等效为一根绕O点转的杠杆，画出这时的动力、阻力、动力臂和阻力臂．