题干

 下列有关化学实验的说法正确的是(       )


A:组装气体发生装置时,遵循自下而上,先左后右的原则

B:在演示实验和分组实验中,为获得最佳实验效果,要尽可能多地添加实验药品

C:振荡试管内溶液时,用手腕力量摆动,不可上下颠动,以防液体溅出

D:向酒精灯里添加酒精时,不得超过酒精灯容积的23,也不得少于容积的13

E:过滤液体时,漏斗里液体的液面不要高于滤纸的边缘,以免杂质进入滤液

F:测定溶液的pH时,应先将pH试纸用蒸馏水润湿

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答案(点此获取答案解析)

A,C,D,E

同类题1

                                                             The advantages of Eating Fruits & Vegetables
      Vegetables and fruit are good for your health because of a lot of vitamins, nutrients(矿物质) and fiber(纤维)in them. Fruits and vegetables are regarded as a healthy diet without adding chemicals or additives(添加剂) for carrying or storing foods. The United States Department of Agriculture suggests eating plenty of fruits and vegetables every day to get the advantages of eating a healthy diet.
Disease Prevention
       The United States Department of Agriculture tells that eating fruits and vegetables helps fight strokes, cardiovascular disease and type 2 diabetes. Because of the potassium in fruits and vegetables, they can prevent the risk of developing kidney stones. The fiber in fruits and vegetables helps the body fight against coronary heart disease.
Idea Health
      Since fruits and vegetables add to a balanced and healthy diet, eating these will help you with your idea. The vitamins in fruits and vegetables helps fight depress(沮丧), according to the Mental Health Foundation. Vitamin B and folic acid found in some vegetables and bananas help you to relax. Eating fruits and vegetables can also help improve memory.
Healthy Weight
      Eating fruits and vegetables helps you have a healthy weight. Fruits and vegetables naturally include less energy than other foods, according to the Center for Disease Control and Prevention. The fiber and water in the fruits and vegetables make you feel that you are full, so you will not feel that you have to eat more food.