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问题 选择题

据中新社报道：2010年我国浪食产量将达到540 000 000 000kg，用科学记数法表示这个浪食产量为      [ ]

 A．54×1010    kg

 B．5.4×1011      kg  

 C．0.54×1012     kg

 D．5.4×1012   kg

答案

答案：B

单项选择题

低温获救的处理哪项不正确（）.

A、保温

B、静卧休息24小时以上

C、给予含酒精饮料

D、体力许可可浸泡于38度～45度水中使体温逐渐恢正常
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单项选择题

In looking at the class structure of an entire system, we may find that its inheritance (1) is either wide and shallow, narrow and deep, or balanced. Class structures that are wide and shallow usually represent forests of (2) classes that can be mixed and matched. Class structures that are narrow and deep represent trees of classes that are related by a common ancestor. There are advantages and disadvantages to each approach. Forests of classes are more loosely (3) , but they may not exploit all the commonality that exists. Trees of classes exploit this commonality, so that individual classes are smaller than in forests. However, to understand a particular class, it is usually necessary to understand the meaning of all the classes it inherits from or uses. The proper shape of a class structure is highly problem-dependent.
We must make similar trade-offs among inheritance, aggregation, and using relation- ships. For example, should the class Car inherit, contain, or use the classes named Engine and Wheel In this case, we suggest that an (4) relationship is more appropriate than inheritance relationship. Meyer states that between the class A and B," (5) is appropriate if every instance of B may also be viewed as an instance of A. The client relationship is appropriate when every instance of B simply possesses one or more attributes of A". From another perspective, if the behavior of an object is more than the sum of its individual parts, then creating an aggregation relationship rather than an inheritance relationship between the appropriate classes is probably superior.

(5)

A．aggregation

B．inheritance

C．association

D．using
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