已知函数f（x）=mx³+2nx²-12x的减区间是（-2，2）。

（1）试求m，n的值；

（2）求过点A（1，-11）且与曲线y=f（x）相切的切线方程；

（3）过点A（1，t）是否存在与曲线y=f（x）相切的3条切线，若存在，求实数t的取值范围；若不存在，请说明理由。

An internet is a combination of networks connected by （） . When a datagram goes from a source to a （） , it will probably pass many （） until it reaches the router attached to the destination network. A router receives a （） from a network and passes it to another network. A router is usually attached to several networks. When it receives a packet, to which network should it pass the packet The decision is based on optimization: Which of the available （） is the optimum pathway

An internet is a combination of networks connected by （）.

A．modems

B．routers

C．switches

D．computers