对Χ射线和γ射线防护而言,由于有关修正因数为1,可以认为()。
A.吸收剂量大于剂量当量
B.吸收剂量小于剂量当量
C.吸收剂量与剂量当量等值
D.以上都不对
参考答案:C
下列关于电源电动势的说法中正确的是( )
A.电源电动势的大小,等于电源没有接入电路时电源两极间的电压的大小
B.闭合电路中,并联在电源两端的电压表的示数就是电源电动势的值;
C.电源提供的电能越多,电源的电动势越大
D.电源的电动势反映了电源将电能转化为其它形式的能的本领
Which of the following most logically completes the argument Alivia’s government has approved funds for an electricity-generation project based on the construction of a pipeline that will carry water from Lake Cylus, in the mountains, to the much smaller Lake Tifele, in a nearby valley. The amount of electricity generated will be insufficient by itself to justify the project’s cost, even if the price of imported oil—Alivia’s primary source of electricity—increases sharply. Nonetheless, the pipeline project is worth its cost, because______.
A.the price of oil, once subject to frequent sharp increases, has fallen significantly and is now fairly stable
B.the project could restore Lake Tifele, which is currently at risk of drying up and thus of being lost as a source of recreation income for Alivia
C.the government of Alivia is currently on excellent terms with the governments of most of the countries from which it purchases oil
D.it would cost less to generate electricity by moving water from Lake Cylus to Lake Tifele than to do so by moving water from Lake Cylus to another valley lake
E.(E) Alivian officials do not expect that the amount of electricity used in Alivia will increase substantially within the next ten years