Persons who are overweight should watch their diet carefully in order to lose pounds. The best way to do this is to start a weight control program. At first it is wise to talk with your doctor. He can advise you of the number of calories（卡路里）you should have in your meals each day. He can tell you about exercising while on your diet. A good rule is to lose slowly. A loss of a pound or two is plenty.
Plan meals around foods you know. This means that it is wise to include foods that you are used to and that are part of your regular eating habits. When you have lost the weight you wish, simple items can be added to your diet so that you can maintain the weight you want. While you are dieting, try to build a pattern of eating that you can follow later to maintain your desired weight.
When dieting, choose low-calorie foods. Avoid such items as fats, fried food, sweets, cakes, cream and soft drinks. Try to take coffee and tea without sugar or cream. Snacks can be part of your diet. For example, a piece of fruit or a simple dessert saved from mealtime can be eaten between meals.
Keep busy! This way you will not be tempted to go off the diet. Make full use of opportunities to exercise. Try walking instead of riding whenever possible. Happy dieting!
While dieting you should ____.（ ）
由原文第二段“When dieting, choose low-calorie foods．”可知B项正确。
把10gMgCl2和MgSO4的混合物溶于适量水中，滴加2mol／L的BaCl2溶液至沉淀完全，共消耗BaCl2溶液25mL。求混合物中MgCl2和MgSO4的质量各是多少克
固定在匀强磁场中的正方形导线框abcd，各边长为1．其中ab是一段电阻为R的均匀电阻丝，其余3边均为电阻可忽略的铜线。磁场的磁感应强度为B，方向垂直纸面向里。现有一与ab段的材料、粗细、长度都相同的电阻丝PQ架在导体框上，如图所示。PQ以恒定速度方向如何
一小物块以速度v0=10m／s沿光滑地面滑行，然后沿光滑曲面上升到顶部水平的高台上，并由高台上飞出，如图所示。问当高台的高度h多大时，小物块飞行的水平距离最大这个距离是多少(g=10m／s2)
某晶体盐的水溶液呈浅绿色，在此溶液中通入氯气，溶液变为棕黄色，把所得棕黄色溶液分成两份：一份加入KSCN溶液，溶液变深红色；另一份加入BaCl2溶液，产生不溶于稀HNO3的白色沉淀，则该晶体盐的化学式是_______。
欲除去乙烷中的乙烯，可将混合气体通过盛有_______的洗气瓶；欲除去乙炔中的硫化氢，可将混合气体通过盛有_______的洗气瓶。
浓硝酸常盛装在棕色瓶中，且贮放在冷暗处，原因是_______，
碳酸氢钠溶液和烧碱溶液反应的离子方程式为_______。
常温下，氨水中存在的离子有_______。
在酸或碱存在的条件下，甲酸甲酯跟水发生水解反应的化学方程式为_______。
有下列几种气体：H2、O2、HCl、NO、NH3、CH4，其中通常情况下能用来和水做“喷泉”实验的是_______。
