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问题 单项选择题

石膏

A．为硅酸盐类物质

B．为碳酸盐类矿物药

C．为硫酸盐类矿物药

D．为汞化合物类矿物药

E．为氧化物类矿物药

答案

参考答案：C

解析：
石膏的化学成分主含含水硫酸钙(CaSO4·2H2O)。故答案选C。

问答题 简答题

CO2在光合作用中的作用
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单项选择题

The Border Gateway Protocol (BGP) is an interautonomous system. ______ protocol. The primary function of a BGP speaking system is to exchange network ______ information with other BGP system. This network reachability information includes information on the list of Autonomous System (ASs) that teachability information traverses. BGP-4 provides a new set of mechanisms for supporting ______ interdomain routing. These mechanisms include support for advertising an IP ______ and eliminate the concept of network class within BGP. BGP-4 also introduces mechanisms that allow aggregation of routes, including ______ of AS paths. These changes provide support for the proposed supernettting scheme.

A. confirmless B. connectionless C. answerless D. classless
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