综合类：阅读理解Cell Phones Increase Traffic
Cell phones are a danger on the road in more ways than one. Two new studies show that talking on the phone while traveling， whether youre driving or on foot， is increasing both pedestrian deaths and those of drivers and passengers， and recommend crackdowns on cell1 use by both pedestrians and drivers.
The new studies， lead-authored by Rutgers University， Newark， Economics Professor Peter D. Loeb2， relate the impact of cell phones on accident fatalities to the number of cell phones in use， showing that the current increase in deaths resulting from cell phone use follows a period when cell phones actually helped to reduce pedestrian and traffic fatalities. However， this reduction in fatalities disappeared once the numbers of phones in use reached a "critical mass" 3 of 100 million， the study found.These studies looked at cell phone use and motor vehicle accidents from 1975 through 2002， and factored in4 a number of variables， including vehicle speed， alcohol consumption， seat belt use， and miles driven. The studies found the cell phone-fatality correlation to be true even when including factors such as speed， alcohol consumption， and seat belt use.
Loeb and his co-author determined that， at the current time， cell phone use has a "significant adverse effect on pedestrian safety" and that “cell phones and their usage above a critical thresholds adds to motor vehicle fatalities." In the late 1980s and part of the 1990s， before the numbers of phones exploded， cell phone use actually had a "life-saving effect" in pedestrian and traffic accidents， Loeb notes. "Cell-phone users were able to quickly call for medical assistance when involved in an accident. This quick medical response actually reduced the number of traffic deaths for a time，" Loeb hypothesizes.
However， this was not the case when cells were first used in the mid-1980s， when they caused a "life-taking effect" among pedestrians， drivers and passengers in vehicles. In those early days， when there were fewer than a million phones， fatalities increased， says Loeb， because drivers and pedestrians probably were still adjusting to the novelty of using them， and there werent enough cell phones in use to make a difference in summoning help following an accident， he explains.
The "life-saving effect" occurred as the volume of phones grew into the early 1990s， and increasing numbers of cells were used to call 911 following accidents， leading to a drop in fatalities， explains Loeb. But this life-saving effect was canceled out6 once the numbers of phones reached a "critical mass" of about 100 million and the "life-taking effect" - increased accidents and fatalities outweighed the benefits of quick access to 911 services， according to Loeb.
Loeb and his co-authors used econometric models to analyze data from a number of government and private studies. He and his co-authors recommend that governments consider more aggressive policies to reduce cell phone use by both drivers and pedestrians， to reduce the number of fatalities.
词汇：crackdown n.制裁，严惩 outweigh v.超过 fatality n.死亡者 econometric adj.计量经济的
hypothesize v.假设，假定
注释：
1. cell：cell phone 的缩写。
2. The new studies， lead-authored by Rutgers University， Newark， Economics Professor Peter D. Loeb ...第一作者为罗格斯大学纽瓦克分校的经济学教授 Peter D. Loeb 的新研究成果……lead-author：第一作者；lead-authored 为动词的过去分 词形式，具有被动意义。罗格斯大学纽瓦克分校是美国新泽西州最负盛名的文理学院。
3. critical mass：临界数量。
4. factored in：包括，把……计算在内。
5. a critical threshold：指的是前文所说的 critical mass.见注释3.
6. was canceled out：被抵消。练习：
1. The two new studies， lead-authored by Professor Peter D. Loeb
A show that talking on the phone while driving or walking in the street increases deaths of drivers and pedestrians.
B show that talking on the phone while driving increases pedestrian deaths.
C recommend that strict measures be taken to restrain cell phone use.
D both A and C.
2. According to the second paragraph， when did cell phones actually help to reduce pedestrian and traffic fatalities?
A Right after cell phones were invented.
B Before the number of cell phone users reached a critical massC When cell phone users totaled to a certain number.
D When the number of cell phones decreased to a certain number.
3. What is said about cell phone use in paragraph 4?
A The number of cell phones in use exploded in the late 1980s and part of the 1990s.
B The number of traffic deaths was reduced in the late 1980s and part of the 1990s due to cell phone use.
C Cell phone users are likely to be involved in traffic accidents.
D The use of cell phones has a life-saving effect for pedestrians and drivers.
4. What is said about cell phone use in the mid-1980s in paragraph 5?
A It had a life-taking effect because there werent enough cell phones in use then.
B The increased use of cell phones then caused a "life-taking effect."C Traffic fatalities increased then because the number of cell phones in use decreased.
D Traffic fatalities decreased then because the number of cell phones in use increased.
5. Which of the following statements DOES NOT answer the question "What caused the "life-saving effect" to occur in the early 1990s?"
A There were more cell phone users during that period.
B The number of cell phone users reached about 100 million.
C More cell phones were used to call 911 when accidents occurred.
D Cell phones enabled people to have quick access to 911 services.
答案与题解：
1. D 根据短文第一段的内容，Loeb 教授的最新研究发现，开车或行路时打手机使司机和行 路人的死亡率上升，并建议采取严厉措施限制司机和行路人使用手机。B 是错误理解， 因为只有行路人被提到。
2. B 短文第二段最后两个句子提供了答案：在手机使用者达到 1 亿的临界点之前，手机的 使用的确减少了交通事故的死亡率。A、C 和 D 的表述内容都没有在文章中提到。
3. B A 是错误选择，因为该段的第四个句子 In the late 1980s and part of the 1990s， before the numbers of phones exploded， ...表明。手机数量在 80 年代末期和 90 年 代早期还未激增。C 的表述内容没有在文章中提到。句子…cell phone use actually had a “life-saving effect”用的是过去式，说的是发生在 80 年代末期和 90 年代早 期的事情，而 D 句用的是一般现在时，表示通常的状况，所以是错误的选择。
4. A第五段的大概意思是，80 年代中期，交通事故的死亡率增加，因为人们还在适应这一 新事物，没有足够的手机让人们在发生交通事故时及时求救。该段没有讨论 80 年代中 期手机数量的增减问题，所以 B、C 和 D 都是错误选择。
5. B第六段最后一个句子说，当手机使用者数量达到 100 万时，life-saving effect 就被 抵消了，life-saving effect 超过了手机使用者能迅速呼叫 911 服务的优点。所以，B 不是问题的答案。其他选项都表述了该段的内容。