GPRS（General Packet Radio ServicE、的中文名称为（）。

B、2.5G

C、3G

D、4G

A．IP Address

B．Radio Service Set ID

C．MAC Address

D．Broadcast SSID in Beacon

A．IP Address

B．Radio Service Set ID

C．MAC Address

D．Broadcast SSID in Beacon

A、雷达频率识别

B、辐射频率识别

C、电子标签

D、雷达快速识别

What Are Mobile Phones?

A mobile phone, also known as a cellphone or cellular phone, is a portable electronic device which behaves as a normal telephone whilst being able to move over a wide area(compare cordless phone which acts as a telephone only within a limited range). Cellphones allow connections to be made to the telephone network, normally by directly dialing the other party's number on an inbuilt keypad. Most current cellphones use a combination of radio wave transmission and conventional telephone circuit switching, though packet switching is already in use for some parts of the cellphone network, especially for services such as Internet access and WAP.

Some of the world's largest cellphone manufacturers include Alcatel, Audiovox, Kyocera(formerly the handset division of Qualcomm), LG, Motorola, Nokia, Panasonic(Matsushita Electric), Philips, Sagem, Samsung, Sanyo, Siemens, SK Teletech, and Sony Ericsson.

There are also specialist communication systems related to, but distinct from cellphones, such as satellite phones and Professional Mobile Radio.

Worldwide Deployment

Cellphones have a long and varied history that stretches back to the 1950s, with hand-held devices being available since 1983. Due to their low establishment costs and rapid deployment, cellphone networks have since spread rapidly throughout the world, outstripping the growth of fixed telephony.

In most of Europe, wealthier parts of Asia, Australia, and the US, cellphones are now widely used, with the majority of the adult, teenage, and even child population owning one. The number of cell phone subscribers in the US has reached over 190 million. The availability of Prepaid or pay as you go services, where the subscriber does not have to commit to a long term contract, has helped fuel this growth.

Standardized Technology

The cellphone has become ubiquitous because of the interoperability of cellphones across different networks and countries. This is due to the equipment manufacturers all working to the same standard, particularly the GSM standard which was designed for Europe-wide interoperability. All European nations and some Asian nations chose it as their sole standard, while in Japan and South Korea another standard, CDMA, was selected.

Cellphone Culture

In less than twenty years, mobile phones have gone from being rare and expensive pieces of equipment used by businesses to a pervasive low-cost personal item. In many countries, cellphones now outnumber land-line telephones, with most adults and many children now owning cellphones. It is not uncommon for young adults to simply own a cell phone instead of a land-line for their residence. In some developing countries, where there is little existing fixed-line infrastructure, the mobile phone has become widespread.

Social Life

With high levels of mobile telephone penetration, a mobile culture has evolved, where the phone becomes a key social tool, and people rely on their cellphone addressbook to keep in touch with their friends. Many people keep in touch using SMS, and a whole culture of "texting" has developed from this. The commercial market in SMS's is growing. Many phones even offer Instant Messenger services to increase the simplicity and ease of texting on phones.

Entertainment

The mobile phone itself has also become a totemic and fashion object, with users decorating, customizing, and accessorizing their cellphones to reflect their personality. Likewise, customized ringtones have been developed.

Etiquette

Cellphone etiquette has become an important issue with mobiles ringing at funerals, weddings, movies and plays. Users often speak at increased volume, with little regard for others nearby people. It has become common practi

A．Y

B．N

C．NG

//收音机 class Radio { void openRadio(Battery battery){ battery.electricityAmount=battery.electricityAmount-10; } } //电池 class Battery { int electricityAmount; Battery(int amount){ electricityAmount=amount; } } //用户测试新买的电池，放进收音机，打开收音机听新闻 public class A { public static void main(String args[]){ Battery nanfu=new Battery(100); System.out.println("南孚电池的储量是："+nanfu.electricityAmount); Radio radio=new Radio(); System.out.println("收音机开始使用南孚电池"); radio.openRadio(【 请填空 】); System.out.println("目前南孚电池的储量是："+nanfu.electricityAmount); } }