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问题 解答题

爸爸今年的年龄是小明年龄的3倍，又已知爸爸比小明大24岁。小明和爸爸今年分别是多少岁？

答案

解：设小明今年x岁，那么爸爸今年就是3x岁，根据题意可得方程：

3x﹣x=24

       2x=24

         x=12

爸爸的今年的年龄：12×3=36（岁）

判断题

自力式调节阀使用中无须有气源或电源。
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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.

(3)

A．dispersive

B．cohesion

C．coupled

D．close-knit
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