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问题 选择题

— _____  is it from school to the library'?

— Two hours.

[ ]

A. How far              

B. How long            

C. How often

答案

答案：B

单项选择题

某企业期末“应收账款”账户为借方余额207000元，其所属明细账户的借方余额合计为280000元，所属明细账户贷方余额合计为73000元，“坏账准备”账户为贷方余额1000元，其中针对应收账款计提的坏账准备为680元，则该企业资产负债表中“应收账款”项目的期末数应是( )。

A．280000元

B．279320元

C．207000元

D．206320元
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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.

(2)

A．free-standing

B．alone

C．only

D．lonely
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