以下为网友提供的英语四级阅读选词填空答案第二套。考试采取“多题多卷”模式，试题顺序不统一，请依据试题进行核对。
So many people use the cell phone frequently every day. But 47 little is certain about the health effects of its use. Manufactures 48 that cell phones meet government standards for safe radio-frequency radiation emission, but enough studies are beginning to document a possible 49 in rare brain tumors (肿瘤), headaches and behavioral disorders in children to cause concern. So far, the evidence isn’t 50 on whether the use of cell phones 51 to any increased risk of cancer. In a new trial, researchers asked 47 volunteers to 52 in a project to measure 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 53 to each ear. During the first scan, the devices were turned off, but for the second scan, the phone on the right ear was 54 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 55 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 activity, and 56 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

答案：

47.N surprisingly

48. H maintain

49. G increase

50. A conclusive

51.B contributes

52.J participate

53. E fixed

54.O switched

55. M regions

56. L provides