Question

以"Using mobile phone is good or bad?"写一篇英语作文！

Answer 1

A mobile or cellular telephone is a long-range, portable electronic device for personal telecommunications over long distances. In addition to the standard voice function of a telephone, current mobile phones can support many additional services such as SMS for text messaging, email, packet switching for access to the Internet, and MMS for sending and receiving photos and video. Most current mobile phones connect to a cellular network of base stations (cell sites), which is in turn interconnected to the public switched telephone network (PSTN) (the exception are satellite phones).
Mobile phones are distinct from cordless telephones, which generally operate only within a limited range of a specific base station. Technically, the term mobile phone includes such devices as satellite phones and pre-cellular mobile phones such as those operating via MTS which do not have a cellular network, whereas the related term cell(ular) phone does not. In practice, the two terms are used nearly interchangeably.The Cell phone is one of the most used pieces of exuitment today. The concept of using hexagonal cells for mobile phone base stations was invented in 1947 by Bell Labs engineers at AT&T (see History of mobile phones) and was further developed by Bell Labs during the 1960s. Radiophones have a long and varied history that stretches back to the 1950s, with hand-held cellular radio devices being available since 1983. Due to their low establishment costs and rapid deployment, mobile phone networks have since spread rapidly throughout the world, outstripping the growth of fixed telephony.
In 1945, the 0G generation of mobile telephones were introduced. OG mobile telephones such as Mobile Telephone Service were not officially categorized as mobile phones, since they did not support the automatic change of channel frequency in the middle of a call, when the user moved from one cell (base station coverage area) to another cell, a feature called "handover."Mock-up of the "portable phone of the future," from a mid-1960s Bell System advertisement, shows a device not too different from today's mobile telephones.
Mock-up of the "portable phone of the future," from a mid-1960s Bell System advertisement, shows a device not too different from today's mobile telephones.
In 1970 Amos Joel of Bell Labs invented "call handoff" that allowed a mobile phone user to travel through several cells during the same conversation. Martin Cooper of Motorola is widely considered to be the inventor of the first practical mobile phone for handheld use in a non-vehicle setting. Using a modern, if somewhat heavy portable handset, Cooper made the first call on a handheld mobile phone on April 3, 1973. At the time he made his call, Cooper was working as Motorola's General Manager of its Communications Division.
Fully automatic cellular networks were first introduced in the early to mid-1980s (the 1G generation). The first fully automatic mobile phone system was the 1981 Nordic Mobile Telephone (NMT) system. Until the late 1980s, most mobile phones were too large to be carried in a jacket pocket, so they were usually permanently installed in vehicles as car phones. With the advance of miniaturization and smaller digital components, mobile phones got smaller and lighter.Luxembourg has the highest mobile phone penetration rate in the world, at 164% in December 2005.[1] In Hong Kong the penetration rate reached 117% of population in September 2004.[2] The total number of mobile phone subscribers in the world was estimated at 2.14 billion in 2005.[3] Around 80% of world's population have mobile phone coverage as of 2006. This figure is expected to increase to 90% by the year 2010.[4]At present, Africa has the largest growth rate of cellular subscribers in the world.[5] African markets are expanding nearly twice as fast as Asian markets.[6] 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 on a monumental scale, not only in Africa but on other continents as well.
All European nations and most Asian and African nations have adopted GSM. In other countries, such as the United States, Australia, Japan, and South Korea, legislation does not require any particular standard, and GSM coexists with other standards, such as CDMA and iDEN.
Some cellular systems are pay as you go, where top-ups can be purchased and added to a phone unit, so there is no monthly bill. Many are "pay monthly", where a bill is issued every month for the amount of calls and text messages made.Since the introduction of mobile phones, concerns have been raised about the potential health impacts from cellular phone use[14]. Studies from the National Cancer Institute and researchers at the Danish Institute of Cancer Epidemiology in Copenhagen do not show any link between cellular phone use and cancer.[15] The Danish study only covered analog mobile phone usage up through 1995, and subjects who started mobile phone usage after 1995 were counted as non-users in the study.[16] However, a study by the International Agency for Research on Cancer of 4,500 users found a statistically significant link between tumor frequency and mobile phone use.Mobile phones and the network they operate under vary significantly from provider to provider, and nation to nation. However, all of them communicate through electromagnetic microwaves with a cell site base station, the antennas of which are usually mounted on a tower, pole, or building.
The phones have a low-power transceiver that transmits voice and data to the nearest cell sites, usually 5 to 8 miles (approximately 8 to 13 kilometres) away. When the mobile phone or data device is turned on, it registers with the mobile telephone exchange, or switch, with its unique identifiers, and will then be alerted by the mobile switch when there is an incoming telephone call. The handset constantly listens for the strongest signal being received from the surrounding base stations. As the user moves around the network, the mobile device will "handoff" to various cell sites during calls, or while waiting (idle) between calls it will reselect cell sites.
Cell sites have relatively low-power (often only one or two watts) radio transmitters which broadcast their presence and relay communications between the mobile handsets and the switch. The switch in turn connects the call to another subscriber of the same wireless service provider or to the public telephone network, which includes the networks of other wireless carriers. Many of these sites are camouflaged to blend with existing environments, particularly in high-scenery areas.
The dialogue between the handset and the cell site is a stream of digital data that includes digitized audio (except for the first generation analog networks). The technology that achieves this depends on the system which the mobile phone operator has adopted. Some technologies include AMPS for analog, and D-AMPS, CDMA2000, GSM, GPRS, EV-DO, and UMTS for digital communications. Each network operator has a unique radio frequency band.

Answer 2

There are advantages and disadvantages for using mobile phone.
firstly, it is good. Using mobile phone can enhance your communication with others. It is a good way to keep in touch with your friends , parents, classments,etc, and when in emergency, you can call your friends or 110 for help.
on the other hand, it is not good. Phones have radiation. Too much radiation is bad for people's healthy. Besides, people usually download games to the phone, it may cause them addict to the games.
All in all, we should use phone properly , not too much.