学校团体操排练队共有学生64人，其中女生人数比男生人数的3倍还少8，团体操排练队共有

数据库系统的核心是______。

有关出血性疾病的描述，不正确的是（）

A.维生素

B.再生障碍性贫血导致血小板生成减少

C.血友病患者凝血功能障碍

D.血小板增多导致凝血功能亢进

E.严重感染可导致血管壁功能异常

管线加油车中的自动释压阀在通常情况下将管线系统中的压力释放至0.02Kpa。（）

The United States government publishes guidelines for appropriate nutrient intakes. These are known as the Recommended Dietary Allowances (RDAs) and are updated regularly based on new research in nutrition. RDAs are suggested amounts of calories, protein, and some minerals and vitamins for an adequate diet. For other dietary substances, specific goals must await further research. However, for the U.S. population as a whole, increasing starch and fiber in one’’s diet and reducing calories (primarily from fats, sugar, and alcohol) is sensible. These suggestions are especially appropriate for people who have other factors for chronic diseases due to family history of obesity, premature heart disease, diabetes, high blood pressure, and high blood cholesterol, or for those who use tobacco.Snacks can furnish about one-fourth of the calorie requirements among teenagers. Those snacks should also provide much of the day’’s allowances for protein, minerals, and vitamins. Sandwiches, fruit, and milk make good snacks for active teenagers. Food from the food pyramid may be part of any meal. A grilled cheese sandwich or a bowl of whole-grain cereal is just as nutritious in the morning as it is at noon. In addition, a good breakfast consists of any foods that supply about one-fourth of the necessary nutrients for the day.

A good breakfast should supply about what percentage of the necessary nutrients for the day

A．One-half.

B．One-third.

C．One-fourth.

D．Less than one-fourth.

进行水系统压力试验中的严密性试验时，达到试验压力后应保压（）并对被测管路进行全面检查。

A.10min

B.30min

C.1h

D.2h