已知三角形ABC中，$\overrightarrow{BA}$$·$$\overrightarrow{BC}$<0，则三角形ABC的形状为（　　）

用修改符号修改病句。

①在小组会上，他总是首先第一个发言。

②马小文穿着一件红上衣，一顶新帽子，真精神。

③读了这本书很受启发。

④我国人口是世界上最多的国家。

根据短文内容，选择正确答案。
C
    Mr. Brown lives in a nice house in a small town with his wife，Mrs. Brown. From Monday to Friday he works in an office near his house. He is free on Saturdays and Sundays. He has a nice garden beside his house. He likes growing flowers and he often works in the garden on Saturdays and Sundays. The flowers are very beautiful and Mrs. Brown likes them very much. She often helps Mr. Brown.

$\sqrt{4}$ ﹣2³÷|﹣2|×（﹣7+5）

下列设备中，哪一个属于计算机网络设备？(   )