[单选题]新机、经过大修或技术改造的机械，应按出厂使用说明书的要求和现行有关（　　）标准进行测试和试运转，特殊机械还应按照有关要求到检测机构进行检测。
A.国家
B.省市
C.行业
D.公司

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 Service). 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
A. It uses the science of nutrition to construct diets in health and disease.
B. It uses the science of nutrition to select foods.
C. It uses the science of nutrition to create diets only for patients.
D. It uses the science of nutrition to prepare foods.

In recent years, there has been a big increase in air travel and many large airports have now reached the limit of the number of aircraft movements they can handle. The problem is made worse by the size of many major cities which prevents the extension of existing airports. Any new airports to be built a long way from city centers will create communication problems and in many countries there simply isn’t enough land for such developments.
Now a new proposal has been put forward which would help to relieve the congestion (拥挤), as far as short flights are concerned. This involves the use of smaller aircraft, carrying about 50 passengers, which only require a short take - off or landing area and which make comparatively little noise because they are propeller -driven (螺旋桨推进). Such aircraft could operate much nearer city centers, say, on disused industrial sites, and give a good service to businessmen and other travelers who are going between centers, which are