题目内容：
So many people use the cell phone so frequently every day. But46 little is certain about the health effects of its use. Manufacturers 47 that cell phones meet government standards for safe radio frequency radiation emission, but enough studies are beginning to document Possible48 in rare brain tumors(肿瘤), headaches and behavioral disorders in children tocause concern. So far, the evidence isn't 49 on whether the use of cell phones 50 to any increased risk of cancer. In a new trial, researchers asked 47 volunteers to 51 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 52 to each ear. During the f'trst scan, the devices were turned off but for the second scan, the phone on the right ear was 53 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 the54 of the brain nearest to the device had higher rates of glucose consumption than therest of the brain. The study shows that cell phones can change brain activity, and 55 a whole new avenue for scientific inquiry, though it doesn' t say anything about whether cell phone radiation can cause cancer.
根据以上内容，回答题．
第46题答案是 ____ 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
参考答案：
答案解析：