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问题 单项选择题

某单回路500kV架空送电线路，位于海拔500m以下的平原地区，大地电阻率平均为200Ω.m，线路全长155km，三相导线a、b、c为倒正三角排列，线间距离为7m，导线采用6分裂LGJ-500/35钢芯铝绞线，各子导线按正六边形布置，子导线直径为30mm，分裂间距为400mm，子导线的铝截面为497.01mm2，综合截面为531.37mm2。

假设线路的正序电抗为0.5Ω/km，正序电纳为5．0×10-6s/km，计算线路的自然功率P应为下列哪项数值？（）

A.956.7MW

B.790.6MW

C.1321.3MW

D.1045.8MW

答案

参考答案：B

单项选择题

SZ206型对开输纸器，纸堆自动上升时，由（）进行纸堆的高度检测。

A.磁开关XK8

B.压纸脚

C.时间继电器

D.限位开关XK2
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单项选择题

Dietetics (营养学) is the application of the science of nutrition (营养) to the selection and preparation of foods, in health and disease. A dietitian is specially trained to give practical advice to individuals about their diets. He/she will have received training in a hospital and/or community setting as part of his/her course. Many dietitians are employed in the NHS (National Health Ser vice). They work with both healthy and sick people as well as their families. With patients who need special diets, dietitians use their scientific knowledge to provide practical information that is appropriate to the patient’s medical history and, lifestyle.

These days a large number of dietitians spend some or all of their time working in the community rather than in a hospital. Many of these have full conditions to apply for registration in public health nutrition as well as being registered dietitians (RD). In the community, the dietitian’s work is more about health education, although many also run clinics (诊所) for people who need specialists’ suggestions about the right diet. Dietitians also work in research, the food industry, government, the media and education. Information about part-time dietitians is available from the Freelance Dietitians Group of the British Dietetic Association.

It is necessary to have a degree (BSc or MSc) in nutrition and dietetics to work as a dietitian. The British Dietetic Association has information about qualifying as a dietitian. There exist undergraduate and postgraduate degrees for a qualified dietitian who has finished required courses.

This passage is mainly about().

A. dietetics

B. health education

C. British Dietetic Association

D. dietitians
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