题目

在高压下，用激光器加热到1800 K时，人们成功制得了原子晶体——干冰，下列推断正确的是（    ） A.该干冰晶体有很高的熔点和沸点                      B.该干冰晶体可用作制冷材料 C.该干冰晶体和石英一样可用作耐磨材料                D.该干冰晶体中的键角是180° 答案：AC 解析:易错原因：完全硬套熟悉的课本中分子晶体——干冰的结构与性质，而错选BD。 仔细审题知，此物质为原子晶体，由原子晶体的性质可知B错，又由SiO2晶体结构可知原子晶体干冰中也存在正四面体结构，也应存在109°28′的键角。This past month saw one of the most devastating storms in history brings death and destruction on the Philippines. The number of lives lost is still being calculated, but it is already sitting above five thousand. In the flurryof news about the storm and its after－math, the cries of “I told you so” from environmentalists rang out loud and clear.　　These scientists were especially vocal during the United Nations Climate Change Conference, which just wrapped up in Warsaw, Poland. The timing of the conference and Typhoon Haiyan was an eerie coincidence, but perhaps the concurrence offered a wakeup call for all.　　Christiana Figures, Executive Secretary of the UN Framework Convention on Climate Change (UNFCCC) said, “We are witnessing ever more frequent extreme weather events, and the poor and vulnerable are already paying the price.”　　Scientists claim that storms like Typhoon Haiyan are an inevitable result of the effect greenhouse gases are having on our environment. Environmental analysts claim that rising temperatures around the globe and changing weather patterns are all part of the same problem.　　This isn’t breaking news. We’ve heard the warnings for years. The UN has been hosting the Climate Change Conference since1995.But the changes that need to be made are huge. Added to this, the developed nations and developing countries have competing interests that are difficult to settle. The issue of who takes responsibility becomes difficult to resolve.　　We may feel far away from Poland and resolving conflicts between countries, but we mustn’t feel far away from the issue. When we watch neighboring countries suffer in severe weather, when we hear reports of increasing global temperatures, when we walk outside and find it difficult to breathe the Shanghai air, we know we have a very real problem. So what are we going to do about it? Are we making every-day choices that can have a positive impact? Are we reducing our carbon footprint? Are we choosing to walk, ride a bicycle or take public transportation instead of a car? Are we recycling? Are we turning off the lights and electronics whenever possible?　　The problem is complex, but saving our earth starts with each of us taking simple steps.1.What is the most terrible typhoon in 2013? It is _________.A. Haiyan??? ???? B. Bebinca????????? C. Danas?? ???????? D.Cimaron2.Warsaw isn’t in Poland，is it?A. Yes, it is?????? B. No, it isn’t????? ? C. Yes, it isn’t ????? D. No, it is3.How many years have we heard the warnings? For nearly ______years.A. 21????? ?????? B. 18???? ???????? C. 19?????? ??????? D. 204.Which of the following is NOT FALSE?A. The environment is worse and worse and we have no ideas about it.B. The environment is worse and we needn’t do anything about it.C. Saving our environment is not so complex.D. The environment is a big problem and we must take simple steps