下列措施中，不可能改变导体电阻大小的是：[ ] A.改变导体的长度 B.改变导体

某有机物在氧气中充分燃烧，生成等物质的量的水和二氧化碳，则该有机物必须满足的条件是[ ]

A．分子中的C．H．O的个数比为1：2：3

B．分子中C．H个数比为1：2

C．该有机物的相对分子质量为14

D．该分子中肯定不含氧元素

若一台三相交流异步电动机转子转速是1440转/分，它是2极电机。

During the project, requirements change for a variety of reasons. As needs change and as work proceeds, additional requirements are derived and changes may have to be made to the existing requirements. It is essential to manage these additions and changes efficiently and effectively. To effectively analyze the impact of the changes, it is necessary that the source of each requirement is known and the rationale for any change is documented. The project manager may, however, want to track appropriate measures of requirements volatility to judge whether new or revised (75) are necessary.

A. proceedings


B. controls
C. forecasting's

D. prelibations

价值工程中的功能一般是指产品的( )。

A．基本功能

B．使用功能

C．主要功能

D．必要功能

下列心绞痛属于不稳定型心绞痛，除了（）

A.初发型心绞痛

B.恶化型心绞痛

C.梗死后心绞痛

D.变异型心绞痛

E.劳力性心绞痛