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问题 选择题

向石灰石、碳酸钠、草木灰、鸡蛋壳等物质中，滴入稀盐酸后，都能产生一种气体，其原因是（　　）

A．这些物质中都含有二氧化碳

B．这些物质都能与盐酸反应生成二氧化碳

C．这些物质都含有碳酸

D．这些物质都是固体

答案

鸡蛋壳、草木灰、石灰石、纯碱等物质中都含有碳酸根，遇酸能反应生成二氧化碳气体，根据所给的四个选项可以得出选项B正确．

故选B

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

6502型电气集中车站办理接车基本进路时，终端按钮表示灯（），说明进路已选出，进路上有关道岔正在转换。

A.亮绿灯

B.闪绿灯

C.灭灯

D.亮白灯
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