问题 选择题

有关金属钠、镁在氯气(Cl2)和二氧化碳中燃烧的化学方程式如下:

①2Na +Cl2===2NaCl   ②2Mg+CO2===2MgO+C 由此获得的认识中,说法错误的是     [ ]

A.②属于置换反应                

B.①②中各元素化合价均发生变化  

C.燃烧不一定要有氧气参加         

D.不是所有可燃物的燃烧都能使用二氧化碳灭火

答案

答案:B

问答题

某工程,建设单位和施工单位按《建设工程施工合同(示范文本)》签订了施工合同,在施工合同履行过程中发生以下事件:

事件1:工程开工前,总监理工程师主持召开了第一次工地会议。会上,总监理工程师宣布了建设单位对其的授权,并对召开工地例会提出了要求。会后,项目监理机构起草了会议纪要,由总监理工程师签字后分发给有关单位;总监理工程师主持编制了监理规划,报送建设单位。

事件2:施工过程中,由于施工单位遗失工程某部位设计图纸,施工人员凭经验施工,现场监理员发现时,该部位的施工已经完毕。监理员报告了总监理工程师,总监理工程师到现场后,指令施工单位暂停施工,并报告建设单位。建设单位要求设计单位对该部位结构进行核算。经设计单位核算,该部位结构能够满足安全和使用功能的要求,设计单位电话告知建设单位,可以不作处理。

事件3:由于事件2的发生,项目监理机构认为施工单位未按图施工,该部位工程不予计量;施工单位认为停工造成了工期拖延,向项目监理机构提出了工程延期申请。

事件4:主体结构施工时,由于发生不可抗力事件,造成施工现场用于工程的材料损坏,导致经济损失和工期拖延,施工单位按程序提出了工期和费用索赔。

事件5:施工单位为了确保安装质量,在施工组织设计原定检测计划的基础上,又委托一家检测单位加强安装过程的检测。安装工程结束时,施工单位要求项目监理机构支付其增加的检测费用,但被总监理工程师拒绝。

指出事件1的不妥之处,写出正确做法。

单项选择题

Within 80 years, some scientists estimate, the world must produce more than eight times the present world food supply. The productiveness of the sea raises our hopes for an adequate food supply in the future. Aided by men of science, we have set forth to find out that 70 percent of the earth remains unexplored--the ocean depths. Thus, we may better discover and utilize the sea’s natural products for the world’s hungry.

It is fish protein concentrate that is sought from the seas. By utilizing the unharvested fish in United States waters alone, enough fish protein concentrate can be obtained to provide supplemental animal protein for more than one billion people for one year at the cost of less than half a cent per day per person. The malnutrition of children is terribly tragic. But the crime lies in society’s unrestrained breeding, not in its negligence in producing fish powder. But wherever the population projects are carefully considered, the answer to the problem is something like this: There are few projects that could do more to raise the nutritional level of mankind than a full-scale scientific effort to develop the resources of the sea. Each year some thirty million tons of food products are taken from the sea, which account for 12 percent of the world’s animal proteins. Nations with their swelling populations must push forward into the sea frontiers for food supplies. Private industry must step up its marine research and the federal government must make new attacks on the problems of marine research development. There is a tone of desperateness in all these designs on the sea.

But what is most startling is the assumption that the seas are an untouched resource. The fact is that the seas have been, and are being, hurt directly and indirectly, by the same forces that have abused the land. In the broad pattern of ecological relationships the seas are not separable from what happens on the land. The poisons that pollute the soil and the air bring in massive doses into the "continental shelf" waters. The dirt and pollution that spills from our urban sewers and industrial out falls despoil our bays and coastal waters. All the border seas are already heavily polluted by the same exploitation drives that have undermined the quality of life on land.

The author’s primary concern is that()

A. the oceans will help to provide enough food for the world in the future

B. thirty million tons of food products are taken from the sea every year

C. city sewers are pouring forth polluted matter into bays and coastal waters

D. a steady increase in population will result in more hungry mouths to feed