B．A good way to improve your math skills

　　C．Benefit from zapping the brain

　　D．Improve math skills by zapping the brain

　　D

　　Some researchers believe that the mobile phone makes youngsters less thoughtful and makes it easier for them to make mistakes in life. Hitting a few keys and then seeing the desired word appear in full trains children to be fast but inaccurate when they do other things, according to scientists. They warn that this could have a negative impact on a whole generation.

　　ChildWise, a market research firm specializing in children's products, found that one in four under­eights had a mobile. The total of 4.5 million youngsters with mobiles included 58 percent of 9 to 10­year­olds, 89 percent of 11 to 12­year­olds, 93 percent of 13 to 14­year­olds and 95 percent of 15 to 16­year­olds.

　　Experts are also concerned about the possible impact of mobile phone radiation on developing brains. But Michael Abramson, a professor at Monash University, Melbourne, Australia, says the amount of radiation transmitted during text messaging is a mere 0.03 percent of that transmitted during voice calls - suggesting radiation is not to blame for the brain effects.

　　In a recent study, Prof Abramson analyzed the mobile phone use of children aged between 11 and 14 and their ability to carry out a number of computer tests. He found that increased mobile phone use appears to change the way their brains work. He said, "The kids who used their phones a lot were faster on some of the tests, but were less accurate. We suppose that using mobile phones a lot, particularly tools like predictive texts for SMS, is training them to be fast but inaccurate. The use of mobile phones is changing the way children learn and pushing them to become more impulsive in the way they behave without thinking things through."

　　The findings follow other research that suggested that text messaging encourages children's language skills and does not damage the ability to spell.

13．It can be concluded from the ChildWise's research that ________.

　　A．the older the child is, the greater chance he has a mobile phone

　　B．children under eight are too young to use mobile phones

　　C．children aged between 11－14 were not involved in the research

　　D．4.5 million people have a mobile phone in Australia

14．Which of the following statements is TRUE according to the passage?

　　A．Prof Abramson thinks mobile phones have little effect on children.

　　B．There's less radiation transmitted during text messaging than during voice calls.

C．Text messaging trains children to be fast and accurate.