《电气设备预防性试验规程》中规定的绝缘电阻值是指（）时的绝缘电阻值。A、10秒 B、

如图所示的电位器实质是一种______，它是靠改变连入电路的电阻线的______来改变电阻值的．

心理学家皮亚杰认为儿童认知发展的前运算阶段处于（）

A．0-2

B．2-7

C．7-11

D．11-15

按照噪声产生的机理，噪声分为( )。

A．机械噪声

B．空气动力噪声

C．电磁性噪声

D．非稳态噪声

E．稳态噪声

根据增值税法律制度的规定，以下单位或者个人中，不属于增值税纳税人的是( )。

A．进口固定资产设备的企业
B．销售商品房的公司
C．零售杂货的个体户
D．生产销售家用电器的公司

During the past years, intelligent technology has evolved (116) three generations. The first was characterized by tools such as prolog and OPS. prolog is a simple backward-chaining environment, and OPS is a simple forward-chaining environment. This led to the second generation of knowledge-engineering environments. Its goal was to model, prototype and construct (117) systems.

All three generations were oriented toward generic (118) and represented generalized implementation environments for the construction of expert systems. knowledge bases and AI applications.Some of the solution-oriented products are also seamlessly integrated with generic knowledge-engineering environments, permitting end users to add (119) rules and objects, as well as predefined knowledge-based logic to address problems in manufacturing simulation.Marketplace orientation is rapidly (120) toward solution-oriented intelligent product environments. the fourth generation represents a new line of thinking and ’ develop-merit by commercial fu-ms. will reduce the cost risk and development time associated with problem solving.

（117）是（）

A. custom

B. knowledge

C. through

D. problem solving