北师大版必修一Unit2Heroes高三英语一轮复习检测卷.doc

Unit 2 Heroes高考一轮复****检测卷
时间：100分钟　　　满分：120分
　选择题部分
第二部分　阅读理解(共两节，满分40分)
第一节(共10小题；每小题3分，满分30分)
阅读下列短文，从每题所给的A、B、C和D四个选项中，选出最佳选项。
A
People love cellphones, which is why nine in ten Americans own one.But does heavy use of cellphones pose a risk of cancer? This question has caused controversy for many years.A new study in rats now augments those concerns.Its data linked long­term, intense exposure to radiation from cellphones with an increased risk of cancer in the heart or brain.The results have yet to be confirmed, the authors note.
Indeed, although the rat study found a link between cellphone radiation and cancer, it offers no clues to why such a link might exist, notes Jonathan Samet.He teaches preventative medicine and directs the Institute for Global Health at the University of Southern California in Los Angeles.Still, he calls the new study's findings “significant”．They could lead to studies researching how cellphone radiation might cause cancer, he says.
Phone signals are relayed between cell towers and cellphones via radio waves.This radio frequency—or RF—radiation is a type known as non­ionizing(非电离的)．Unlike X­rays, non­ionizing radiation does not deposit enough energy into cells to release electrons from atoms or molecules, producing ions.So it lends to be far less harmful than ionizing radiation, such as X­rays.But that does not mean radio waves might not cause harm.
In very large doses(量) this radiation will heat the body and cause tissue damage.But it's not yet known what much lower RF levels might do, such as those from cellphone use.Five years ago, the World Health Organization's International Agency for Research on Cancer, or IARC, concluded that cellphone use “is possibly careinogenic(致癌的)”．
Its conclusion was based on what little research data was available at that time.But notice that IARC was not certain.It said only that phone use might “possibly” cause cancer.So scientists at the National Toxicology Program, or NTP, investigated fur