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问题 单项选择题

ADO对象模型用于简化通过ODBC，OLEDB等接口访问数据库的编程工作。下列关于ADO的说法错误的是（）

A.用ADO对象访问数据库时，仍需依赖OLEDB，ODBC等数据库访问接口

B.开发者只需通过使用ADO对象模型中的几个简单对象的方法和属性即可实现对数据库的访问，因此，使用ADO对象模型可以提高数据访问效率

C.ADO是在OLEDB，ODBC等接口基础上设置的高一层接口

D.ADO对象模型提供的编程接口与数据提供者无关，提高了数据访问的透明性

答案

参考答案：B

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.

(1)

A．distinction

B．level

C．grade

D．hierarchy
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多项选择题

比例调节器（P调节器）一般采用反相输入，具有（）特性。

A、延缓性

B、输出电压和输入电压是反相关系

C、积累性

D、快速性

E、稳定性
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