旅客按不同团体旅客分类的话可分为（）

A、旅行团体

B、劳务输出团体

C、竞技及文艺团体

D、社会组织团体

Bluetooth is a universal radio interface in the (1) frequency hand that enables portable electronic devices to connect and communicate wirelessly via short-range, ad hoc networks. Each unit can simultaneously communicate with up to (2) other units per piconet. Moreover, each unit can simultaneously (3) to several piconets. Eliminates the need for wires, cables and connectors for and between cordless or mobile phones, modems, headsets, PDAs, Computers, printers, projectors, local area networks, and so on, and paves the way for new and completely different devices and applications. Technology Characteristics (4) symbol rate exploits maximum available (5) bandwidth。

5（）

A．messages

B．certificates

C．applets

D．channel