Radiation occurs from three natural sources: radioactive material in the environment, such as in soil, rock, or building materials; cosmic rays; and substances in the human body, such as radioactive potassium in bone and radioactive carbon in tissues. These natural sources account for an exposure of about 100 millirems a year for the average American.
The largest single source of man-made radiation in medical x-rays, yet most scientists agree that hazards from this source are not as great as those from weapons-test fallout, since strontium-90 and carbon-14 become incorporated into the body, hence delivering radiation for an entire lifetime. (46) The issue is, however, by no means uncontroversial; indeed, the last two decades have witnessed intensified examination and dispute about the effects of low-level radiation.
A survey conducted in Britain confirmed that an abnormally high percentage of patients suffering from arthritis of the spine who had been treat
Turkey’s Bodrum peninsula is different. The tourist boom in this part of the world (1) turned some small villages into resorts yet left neighbouring beaches undisturbed, making it quite (2) southern France or the Spanish Coasts where few stretches of coastline are undevelopeD．
The (3) for this happy set of circumstances is simple. For thousands of years, travel here (4) easier by boat than by lanD．So when mass tourism arrived in the (5) 1980s, there was no coast road for ribbon development to follow. So the peninsula, just (6) hour from Bodrum airport, has not become one long littoral of resort.
The building (7) new hotels has mainly been confined to places easily reached by then relatively (8) roads. Such ease of access has made Gumbet, near Bodrum, a busy resort, while the little fishing village of Gumusluk, 12 miles further west and only recently reachable by (9) , remains tranquil and undistu
| The tragic impact of the modern city on
the human being has killed his sense of aesthetics, the material benefits of a
wealthy society have diverted his attention from his city and its cultural
potentials to the products of science and technology: washing machines, central
heating, TV sets, computers and cars. He is a car driver and reluctant to walk. Without adequate parking facilities, the streets are littered with cars. Congestion (堵塞) has become the predominant factor in his environment, and statistics suggest that two cars per household may make matters worse. Meanwhile, insult is added to injury by "land value". The value of land results from its use. When its use is intensified, its value rises. "Putting land to its highest and best use" becomes the principal economic standard in urban growth. This specu A. were more enthusiastic about the development of science and technology B. had a stronger sense of beauty C. over-dependent on labor saving devices D. paid more attention to material benefits [单选题]施工机具应有（）存放，库房要经常保持干燥、通风。
A.指定库房 B.专用库房 C.统一库房 D.临时库房 [单项选择]某写字楼当前市场售价为22000元/㎡，业主采用年租金6%等比递增方式出租，并希望在20年的出租期内租金收入的现值之和与当前售价相等。如果年利率为6%，则第一年的租金应该确定为（ ）元/㎡。
A. 1283 B. 1318 C. 1166 D. 1320 [单选题] “未携带许可证经由道路运输烟花爆竹”行为的违法主体是烟花爆竹的( )
A. 发货人 B. 托运人 C. 收货人 D. 承运人 [简答题]进出库成本公式？
[判断题]所有吊物孔、没有盖板的孔洞、楼梯和平台，应装设不低于1000mm高的栏杆和不低于100mm高的护板。
A.正确 B.错误 [单选题]九联圩回段列车清客完毕后遇乘客抢上，司机应（ ）。
A.立即降级开门 B.让乘客从司机室下车 C.让车站人员上车防护 D.报行调申请二次清客 我来回答: 提交
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