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问题 单项选择题

进入涉及煤气的设施内一氧化碳含量高大于（）ppm或氧气含量低19.5%时，应佩戴空气或氧气呼吸器等隔离式呼吸器具；设专职监护人员。

A、24

B、30

C、40

D、50

答案

参考答案：D

单项选择题

As a project manager, you are aware that estimating schedule activity costs involves developing an approximation of the costs of the resources needed to complete each schedule activity. In approximating costs, the estimator considers the possible causes of variation of the cost estimates, including risks. Cost estimating includes identifying and considering various costing alternatives. For example, in most application areas, additional work during a design phase is widely held to have the potential for reducing the cost of the execution and product operations. The cost estimating process considers whether the expected savings can offset the cost of additional design work. Cost estimates are generally expressed in units of currency to facilitate comparisons both within and across projects. Cost estimates can also benefit from refinement during the course of the project to reflect on the additional detail available. For your project, which is in the initial phases, your team suggested a rough order of magnitude estimate—this could be in the range of （）.

A．-75% to+125%

B．-50% to+100%

C．-25% to+50%

D．None of the above
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问答题 简答题

正常生产中工艺反应103-J调速器PV-6波动，请分析原因并作出处理？
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