Sometimes I feel that being the mother of three small children is like operating a large circus(马戏团)． 21 afternoon last week, my three sons playing peacefully in the back yard ( 院子), 22 the ball from one to another．I jumped at the chance to talk to one of my friends 23 the phone, but before I 24 to the phone, I could tell the boys had begun to quarrel with each other about something．I rushed out to 25 peace,but before I got there Charles had 26 a rock at Mark,and hit him in the eye．By the time I got to the back yard,they had begun to 27 about this．Even David,the oldest boy,who won' t usually fight with anybody about 28 ,was involved(卷入) First,! 29 them stop fighting, and then ! examined Mark' s eye．I decided that it wasn' t going to develop into a black eye, but I felt that they should 30 at least a little for 31 they had done．"I' m going to 32 to your father about this when he comes home tonight,"I said．"He and I will think of how to punish you．"Things were 33 quiet after that for about half an hour, and then Charles 34 a glass in the kitchen,and at almost the same 35 ,Mark fell out of the apple tree．
第（28）题答案
词义辨析题。这里是指“不为任何事情和任何人打架”。anything任何事情，符合句意。
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_______。
