将一定质量铜锌合金的粉末加入到一定质量的硝酸银溶液中，充分反应后过滤，向滤渣中滴

In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet.

How does the developer of a large database system achieve (1) and data independence How does the developer make certain that stored items are (2) and do not simply disappear in the immensities of the database, as if in quicksand

One solution is to set up a (3) system, in which all data (the internal level), all records and files (the conceptual level), and all user interfaces (the external level) are controlled by one central programming group. This may seem the most useful solution. But worldwide enterprises such as the meteorological and satellite tracking networks, IBM, and General Motors gather and record information at a very large number of locations. To stay flexible and avoid top - heaviness, such an organization might want to avoid excessive centralization.

A centralized system is (4) , but it may not be responsive to user needs. This is particularly true in a large organization - the worldwide meteorological network, for example, Data-gathering methods in the Himalayas, the equatorial jungles are different in very possible way. It is reasonable to believe that the best choices for the corresponding data storage and access structures ought to be just as different. A centralized database system would not (5) such differences.

4（）

A．good

B．inefficient

C．efficient

D．useful

下列属于投资性房地产的是( )。

A．企业生产经营用的土地使用权

B．企业出租给本企业职工居住并按市场价格收取租金的宿舍

C．持有并准备增值后转让的建筑物

D．企业拥有的已部分出租的旅馆中，能够单独计量的出租部分

某人突发高烧, 医生会建议先服用一些解热镇痛药物。下列药品中可用作退烧药的是

A．阿司匹林

B．三硅酸镁

C．环丙沙星

D．阿莫西林

营业线隧道改建对围岩进行扩挖时，应及时支护。当利用原衬砌作支撑点时，应采用环形支撑，并符合下列规定：（）

A.对原衬砌的受力部位必须加密钢拱架

B.拆除原有衬砌前，没必要对原衬砌背后围岩加固

C.各纵梁之间应连接牢固，必要时起拱线以下亦应支撑

D.扩大部位的支柱应沿拱圈的辐射方向架设，并左右对称

E.列车到达前，洞内外应立即撤除所有障碍，所有施工人员必须撤至安全地点待避

地球上可观测到的紫外线辐射全波段为（）。

A.300-400nm

B.280-400nm

C.290-400nm

D.100-400nm