9．Holding a cell phone against your ear or storing it in your pocket may be dangerous to your health．This explains a warning that cell phone manufacturers include in the small print that is often ignored when a new phone is purchased．Apple，for example，doesn't want iPhones to come closer to you than 1.5centimeters； Research In Motion，BlackBerry's manufacturer，recommends 2.5centimeters．
If health issues arise from cell phone use，the possible effects are huge．Voice calls-Americans chat on cell phones 2.26trillion（萬億）minutes annually-earn $109billion for the wireless carriers．
Devra Davis，an expert who has worked for the University of Pittsburgh，has published a book about cell phone radiation，"Disconnect．"The book surveys scientific research and concludes the question is not settled．
Brain cancer is a concern that Ms．Davis examines．Over all，there has not been an increase in its incidence since cell phones arrived．But the average masks an increase in brain cancer in the 20-to-29age group and a drop for the older population．
"Most cancers have multiple causes，"she says，but she points to laboratory research that suggests low-energy radiation could damage cells that could possibly lead to cancer．
Children are more vulnerable（易受傷的）to radiation than adults，Ms．Davis and other scientists point out．Radiation that penetrates only five centimeters into the brain of an adult will reach much deeper into the brains of children because their skulls are thinner and their brains contain more absorptive fluid（易吸收的液體）．No studies have yet been completed on cell phone radiation and children，she says．
Henry Lai，a research professor in the bioengineering department at the University of Washington，began laboratory radiation studies in 1980and found that rats exposed to radiation had damaged DNA in their brains．
Ms．Davis recommends using wired headsets or the phone's speaker．Children should text rather than call，she said，and pregnant women should keep phones away from the abdomen（腹部）．
24．According to Ms Davis，brain cancer increaseC．
A．a(chǎn)mong children B．a(chǎn)mong old people
C．in the twenties D．a(chǎn)mong pregnant women
25．Why do children easily be affected by radiation？D
A．Because they haven't grown up．
D．Because their skulls are thinner and their brains are easily hurt．
C．Because they use cell phones more often than adults．
B．Because they are too young to protect themselves．
26．What can we conclude from the last paragraph？B
A．Pregnant women should keep cell phones away．
B．People should use cell phones in the correct way．
D．When you use a cell phone，use a wired headset or the phone's speaker．
C．If you are a child，you'd better text than make phone calls．
27．What does the passage mainly talk about？A
A．Be careful when using cell phones．
D．Low-energy radiation could damage cells that could lead to cancer．
C．Rats exposed to radiation have damaged DNA in their brains．
B．Don't hold your cell phone against your ear．
分析 本文講述的是使用手機會帶來輻射的負影響，因此需要正確使用手機．
解答 24 C．細節(jié)理解題．根據(jù)第四段"But the average masks an increase in brain cancer in the 20-to-29 age group and a drop for the older population"可腦癌主要發(fā)生在20多歲的時候，故選C項．
25 D．細節(jié)理解題．根據(jù)"Radiation that penetrates only five centimeters into the brain of an adult will reach much deeper into the brains of children because their skulls are thinner and their brains contain more absorptive fluid（易吸收的液體）"可知，小孩更容易受輻射的影響是因為他們的頭骨更薄，大腦更容易受傷，故選D項．
26 B．推理判斷題．最后一段"Ms．Davis recommends using wired headsets or the phone's speaker．Children should text rather than call，she said，and pregnant women should keep phones away from the abdomen"所講述的都是一些正確使用手機以防止輻射的影響的方法，由此判斷選B項．
27 A．主旨大意題．本文主要介紹使用手機的負作用，最后警示人們要正確使用手機．因此A項更能說明全文的主旨，而其它三項只是文中的細節(jié)內(nèi)容，故選A項．
點評 本文是科教類閱讀理解．做這類題材閱讀理解時要求考生對文章通讀一遍，做題時結(jié)合原文和題目有針對性的找出相關(guān)語句進行仔細分析，結(jié)合選項選出正確答案．推理判斷題也是要在抓住關(guān)鍵句子的基礎上合理的分析才能得出正確答案，切忌胡亂猜測，一定要做到有理有據(jù)
