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 tends 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 carcinogenic(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 further.

　　【解题导语】　本文是一篇说明文。人们喜欢用手机，90%的美国人都有手机。那么，过度使用手机是否会有患癌的风险呢？一项新的研究给出了一些线索。

　　1．Which of the following can replace the underlined word "augments"？

　　A．figures out B．puts out

　　C．refers to D．adds to

　　D　解析：词义猜测题。画线词前面提到过度使用手机是否有患癌的风险这一问题多年来引发的争议不断，再根据画线词后的"concerns"和"Its data linked long­term, intense exposure to radiation from cellphones with an increased risk of cancer in the heart or brain."可知，现在一项在老鼠身上进行的新研究增加了那些忧虑。故画线词与adds to意义相近。

2．In which aspect does Jonathan Samet think the new study in rats is significant?