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问题 多项选择题

未来中国将形成以西部、北部各电源基地为主要送端，（）为主要受端的大范围、大规模跨区输电格局。

A.华北京津冀鲁

B.华中东四省

C.华东

D.东北

答案

参考答案：A, B, C

填空题

海洋约占地球表面积的71%，海水化学资源的利用具有非常广阔的前景．镁及其合金是一种用途很广的金属材料，目前世界上60%的镁是从海水中提取的，其主要步骤如下：

①为了使MgSO4转化为Mg（OH）2，试剂①可以选用______，

②试剂②可以选用______；

③试从节约能源、提高金属镁的纯度分析，以下适宜的冶镁方法是______．

A．Mg（OH）2

△
MgO
电解
2800℃
Mg

B．Mg（OH）2

△
MgO
C
还原
Mg

C．Mg（OH）2

HCl
MgCl2
电解
714℃
Mg

D．Mg（OH）2

HCl
MgCl2
活泼金属
还原
Mg

④写出电解制备镁的化学方程式______．
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单项选择题

UML-based tools are often used for J2EE/.NET application analysis and design，both because UML’s object orientation is ideal for the J2EE/.NET implementation (66) and because of the expanding scope and complexity of today’s enterprise endeavors． (67) the approaches diverge at the coding/implementation phase，a common Set of analysis and design techniques applies to both J2EEand.NET．

The use of a virtual machine (VM) architecture is also common to J2EE and .NET. Application development tools (68) intermediate-level code instead of platform-specific binary code, which means the VM interprets that code in real time or performs Just-In-Time (JIT) compilation; the Microsoft VM always runs JIT-compiled code. This VM-based model results in (69) -independent applications and is conducive to the late-binding technique that’s (70) to the OO approach.

（69）（）

A.platform

B.framework

C.operation

D.computer
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