2. 外语
  3. So many people use the cell phone so frequently every day. But 【C1】______ little is certain about the health effects of its use.

So many people use the cell phone so frequently every day. But 【C1】______ little is certain about the health effects of its use.

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问题    So many people use the cell phone so frequently every day. But 【C1】______ little is certain about the health effects of its use. Manufacturers 【C2】______ that cell phones meet government standards for safe radio-frequency radiation emission, but enough studies are beginning to document a possible 【C3】______ in rare brain tumors (脑瘤), headaches and behavioral disorders in children to cause concern. So far, the evidence isn’ t【C4】______on whether the use of cell phones【C5】______to any increased risk of cancer. In a new trial, researchers asked 47 volunteers to 【C6】______ in a project to censure glucose (葡萄糖) consumption in the brain by scanning the brain to see how cells use energy. For both 50-minute scans, the volunteers had a cell phone【C7】______to each ear. During the first scan, the devices were turned off, but for the second scan, the phone on the right ear was【C8】______on and received a recorded-message call, although the volume was muted (消音) so the noise wouldn’ t bias the results. The results of the second scan showed that the 【C9】______ of the brain nearest to the device had higher rates of glucose consumption than the rest of the brain. The study shows that cell phones can change brain activities and【C10】______a whole new avenue for scientific inquiry, though it doesn’t say anything about whether cell-phone radiation can cause cancer.
   A) conclusive B) contributes C) derive D) expresses
   E) fixed F) immensely G) increase H) maintain
   I) mission J) participate K) particular L) provides
   M) regions N) surprisingly O) switched
【C4】
选项
答案A
解析 空格前为系动词否定形式，空格处应该填一个形容词。根据句子意思，到目前为止，手机的使用是否会增加患癌症的风险，证据依然无法确凿。exclusive意为“确凿的”，符合题意，故选A。
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