Recently, more than 2,000 high school teachers have been asked about the effect of the Internet on their students. Teachers say the Internet has had a good influence（影响）and a not-so-good influence on this generation.
Three quarters of the teachers say the Internet and search tools have had a great effect on their students' research habits and skills. But 87 percent agree that this young generation don' t know about hard work and can' t stay attentive（注意力集中的）for long. And 64 percent say the Internet does more to distract（使分心）students than to help them in their studies. Many students think "doing research" just means doing a quick search on Google.
According to the teachers, one problem is that students trust too much of the information on the Internet. These students have not developed skills to judge the quality of the information. It's something that really has to be taught and paid attention to. It's like everything else. In a world where things can happen quickly, you really need to have a way to step back, think and make judgment about the information you have. And teachers can do a lot to teach that.
Another problem is that being able to quickly find information keeps the students from working hard. They become dependent on search tools and do not make enough use of printed books. Many teachers are also afraid that the Internet makes it easy for students to copy work done by others.
What will happen when students depend too much on search tools?（ ）
事实细节题。由最后一段第二句可知，中学生过于依赖搜索工具而没有充分利用书籍。故B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_______。
