问题
单项选择题
单糖浆的制备方法是
A．研磨法
B．化学反应法
C．蒸馏法
D．稀释法
E．溶解法
答案
参考答案：E
解析：糖浆剂的制备方法有溶解法(包括热溶法、冷溶法)和混合法。
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单糖浆的制备方法是
A．研磨法
B．化学反应法
C．蒸馏法
D．稀释法
E．溶解法
参考答案：E
解析：糖浆剂的制备方法有溶解法(包括热溶法、冷溶法)和混合法。
（8分）化学反应的程度与反应物的量之间有一定的规律可循。下面是小明同学各取等质量的木炭和铁丝分别在容积相同的集气瓶中燃烧，请帮助他把横线填写完整。
| 实验 | 实验步骤 | 实验现象 | 反应的文字表达式 | |
| A木炭 | 在空气中 | 红热 | 生成气体使澄清的石灰水变浑浊 |
|
| 在氧气中 | ，放热 | |||
| B铁丝 | 在空气中 | 不燃烧 |
| |
| 在氧气中 | 剧烈燃烧， ， 生成黑色固体。 | |||
| 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. |
Why are RDAs regularly updated
A．New discoveries in the science of nutrition are constantly being made.
B．Americans’ diets are constantly changing.
C．As people age, their nutritional needs change.
D．Very little is currently known about nutrition.