题目内容
（请给出正确答案）
A.STRAIGHTEN
B. STRAIGHTENING
C. VANES
D. STRAIGHTENING VANES
参考答案
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更多“按照美国GAS ASSOCIATION标准在823DP电动差压变送器前面安装一个（）”相关的问题
A.STRAIGHTEN
B.STRAIGHTENING
C.VANES
D.STRAIGHTENING VANES
A marine chemist issues gas free certificates and is certified by which organization？
A.Mine Safety Appliance Association
B.American Chemical Society
C.Marine Chemists Association
D.National Fire Protection Association
A.杜威
B.阮冈纳赞
C.杜定友
D.刘国钧
RS-232C是由美国电子工业协会(EIA：Electronic Industries Association)推荐的标准接口，它是应用于______交换的数据通信设备和数据终端设备之间的标准接口。
A.1780
B.1870
C.1900
D.1930
The One-Call System
In most states, natural gas industry-supported laws require contractors and private landowners to call the local One-Call number before beginning any kind of digging. With forty-eight hours' notice, a pipeline operator will locate the pipeline and mark it clearly. Any damage at all to a pipe-even the slightest scratch could lead to a leak later on. Whether One-Call has become the law in your state or not, you can help keep pipelines safe by calling the number on the right-of-way markers before you dig. 2. Leak Detection
Most pipelines are operated twenty-four hours a day from a control station, using telephone, satellite, or microwave communications systems. Computers are widely used to monitor conditions along the line every ten to sixty seconds, sounding an alarm if they detect any abnormality or sudden change in pressure. In the event of an alarm, valves can be closed and nearby pipeline crews dispatched within minutes.
3. Emergency Response Preparedness
Although leaks occur infrequently and rarely result in a fire, readiness for any emergency is a crucial responsibility for pipeline companies. Federal and state laws supported by the natural gas industry require pipeline companies and local police and fire departments to maintain a coordinated plan of response and to practice for an emergency by staging drills. These drills and personnel training programs emphasize the need for immediate action and for cooperation between the various rescue agencies and the pipeline company.
4. Public Awareness
The One-Call system, state-of-the-art leak detection equipment, and emergency response procedures have all been put in place with one thing in mind-the safety of you, the public. Please visit the website of the Natural Gas Association to find out more about our safety procedures, tips for using natural gas safely in your home, and information on what to do if you see someone tampering with pipeline right-of-way markers.
What is the main focus of this passage？
A．Safety
B．Personnel training
C．Computer monitoring
D．Industry-supported laws
薪水信息和职业统计。
(i)估计一个将每场得分(points)与加入联盟年数(exper)、年龄(age)、大学期间打球年数(coll)相联系的模型。包含一个exper的二次项，其他变量都应该以水平值形式加入模型。按照通常的格式报告结果。
(ii)保持大学打球年数和年龄不变，从加入联盟的第几个年份开始，在NBA打球的经历实际上将降低每场得分？这讲得通吗？
(iii)你为什么认为coll具有负系数，而且统计显著？(提示：NBA运动员在读完大学之前被选拔出，甚至直接从高中选出。)
(iv)有必要在方程中增加age的二次项吗？一旦控制了exper和coll之后，这对年龄效应意味着什么？
(v)现在将log(wage)对points，exper，exper2，age和coll回归。以通常的格式报告结论。
(vi)在第(v)部分的回归中检验age和coll是否联合显著。一旦控制了生产力和资历，这对考察年龄和受教育程度是否对工资具有单独影响这个问题有何含义？
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