Mobile phone history
    Not long ago， mobile phones were used mainly by business people and government officers in society． In the US， mobile phone users were about 340，000 in 1985． Now there are 205 million mobile phone users in the US． Studies also show that over 50 percent of children in the US own their own personal mobile phones． The mobile phone explosion （激增） has led to a huge number of waste phones． The number of mobile phones users has also increased throughout the world． In the middle of 2005， the number of total users jumped to 2.4 billion worldwide．
    Mobile phone waste
    When people throw their mobile phones away， they usually end up in the open air． Mobile phones include some materials like lead， mercury and cadmium． They can go into public drinking water and food and do harm to people's health． About 75 percent of mobile phone users don't throw their phones away． Instead， they prefer to keep the waste ones sitting around the house as they are not worth very much． People are also afraid that others may know their information if they sell their waste phones． Less than 20 percent of them are recycled each year．
    Benefits （益處） of recycling mobile phones
    Mobile phones have valuable materials inside． The most valuable material is gold， which is used in the phone circuit boards． Recycling can reduce greenhouse gas emissions （排放物） and keep natural resources like gold． If all of the waste phones in the US are recycled， it will save enough energy to offer over 194，000 U．S． families electricity （電力） for one year．
    How mobile phone recycling works
    Many people do not know how mobile phone recycling works． One method of recycling mobile phones is to take the working parts of broken phones， then combine （使結(jié)合） them with the working parts of other used mobile phones to make one ready-to-use mobile phone． Another method of mobile phone recycling is to melt （熔化） down and separate parts of the phone， getting the valuable natural resources， such as gold and platinum． Plastic and glass can also be recycled from used mobile phones．

The used mobile phones
Mobile phone history	Compared with the condition in 1985， there are（1） 205 million 205 million mobile phone users at present． More than （2） 50 percent 50 percent of the children in America have their own personal mobile phones． It has （3） led to led to a huge number of waste phones because of the mobile phone explosion．
Mobile phone waste	Some materials， such as lead， mercury and cadmium in the mobile phones are （4） harmful harmful to people's health． Three-quarters of the users would rather（5） keep keep the waste ones sitting around the house．
Benefits of recycling	Some materials are of great（6） value value ． They can be used again． It can（7） save save plenty of electricity for American families if the waste phones are recycled．
How recycling （8） works works	One way is to join working parts of（9） broken phones broken phones or used phones together． We can also melt down and separate parts of the phone to（10） get get natural resources．