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问题 选择题

在两份质量相等，溶质质量分数相同的盐酸中，分别加入56 g铁和若干克碳酸钙，都恰好完全反应，所得溶液质量相等，则所加碳酸钙的质量为（　　）

A．56g

B．54g

C．96.4g

D．100g

答案

要使天平两端质量再次相等，则两烧杯中的溶液反应前后物质的质量增加值应该相等，利用差量法解决此题．

设放入铁后溶液质量增加的质量是x，放入的碳酸钙质量是y

Fe+2HCl=FeCl2 +H2↑    溶液质量增大

56                  2      56-2=54

56g                          X

56
56g
54
x
     X=54g

CaCO3+2HCl=CaCl2+H2O+CO2↑ 溶液质量增大

100                      44    100-44=56

Y                                 54g

100
y
=
56
54g
    Y=96.4g

故选C

填空题



For more than two centuries, American’s colleges and universities have been the backbone of the country’s progress. They have educated the technical, managerial, (1) and provided generation after generation of national leaders. Today educators from around the globe are turning to U. S. institutions of higher learning (2) . They are apt to find many reasons for the excellence of American universities, but (3) stand out as watersheds:
Education (4) : In 1862 Congress enacted the Land-Grant College Act, which essentially extended the opportunity of higher education (5) , including such disenfranchised groups as women and minorities. Each state was permitted to sell large tracts of (6) and use the proceeds to endow at least one public college.
(7) : Over the years, the decentralization and diversity of the America’s colleges and universities have promoted competition for students and resources. Competitive pressure first arose (8) . The academy’s impact really grew after World War II, when (9) commissioned by President Roosevelt argued that it was the federal government’s responsibility to (10) for basic research. Instead of being centralized in government laboratories, scientific research (11) in American universities and generated increasing investment. It also gave graduate students research opportunities and helped (12) far and wide, to the benefit of industry, medicine and society as a whole.
(13) : The end of the World War II saw passage of the Servicemen’s Readjustment Act of 1944. The law, which provided for (14) for returning veterans, made an already democratic higher-education system accessible in ways that were (15) in Europe, opening the doors of the best universities to men and women who had (16) of going to college.
(17) : The creation of federal loan guarantees and subsidy programs, as well as outright grants for college students brought (18) to higher education and further helped to democratize access. Since its founding (19) , the Federal Family Education Loan Program has funded more than 74 million student loans worth more than (20) .
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单项选择题 A1型题

鸡新城疫最常用的抗体检测方法是（）。

A.ELISA

B.HA和HI

C.AGP

D.IFA

E.PCR
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