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) .

1（）

A.Client

B.Editor

C.Creator

D.Server

如图所示，质量为m=1.0 kg的物体置于水平地面上，对物体施以F=6 N的水平拉力作用一段时间t₁后撤去，物体便以大小为a=4 m/s²的加速度做匀减   速运动，t₂=1 s后静止(g=10 m/s²)，求：

(1)物体与水平地面间的动摩擦因数μ；

(2)拉力F作用的时间t₁。