题目内容
（请给出正确答案）
A.4
B.5
C.7
D.14
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更多“水泥混凝土整体面层铺设施工质量控制要求整体面层施工后，养护时间不应少于()天”相关的问题
卫生洁具必须要有完整的安装说明书。
卫生间、厨房地面应比客厅地面低()。
A.10mm
B.5mm
C.20mm
D.15mm
卫生器具交工前应做满水和通水实验。
地漏标高应低于卫生间地面标高()。
A.20mm
B.l0mm
C.5mm
D.15mm
顶棚漏水处理应为()。
A.物业公司
B.设计院
C.施工单位
D.监理单位
整体面层施工后，养护时间不应小于()d；抗压强度应达到5MPa后，方准上人行走。
A.5
B.7
C.14
D.28
整体面层施工后，养护抗压强度应达到()MPa后，方准上人行走。
A.1.2
B.2
C.5
D.10
预防卫生间顶棚漏水预防措施()。
A.控制找平层质量
B.厕、浴、厨房间在未施工防水前都必须全部进行蓄水检验，蓄水时间不少于24h，蓄水高度不小于50mm
C.找平层表面应抹平压光、坚实平整，不起砂
D.涂膜防水层做完之后，严格加以保护，在保护层未做之前，任何人员不得进入，也不得在卫生间内堆积杂物，以免损坏防水层
E.防水层施工后，进行蓄水试验。蓄水深度必须高于标准地面20mm，24h不渗漏为止，如有渗漏现象，可根据渗漏具体部位进行修补，或全部返工。监理公司应对防水工程做专项验收。
卫生间墙面防水高度设置为()。
A.1000mm
B.1800mm
C.2000mm
D.1500mm
顶棚渗漏原因可能有()。
A.防水层质量不合格
B.找平层质量不合格
C.未修补基层、认真清扫找平层
D.防水层起泡、剥离
E.防水层遭破坏
某医院门诊楼，位于市中心区域，建筑面积28326m2，地下1层，地上10层，檐高33.7m。框架剪力墙结构，筏板基础，基础埋深7.8m，底板厚度1100mm，混凝土强度等级C30，抗渗等级P8。室内地面铺设实木地板，工程精装修交工。2008年3月15日开工，外墙结构及装修施工均采用钢管扣件式双排落地脚手架。
事件一：2008年6月1日开始进行底板混凝土浇筑，为控制裂缝，拌制水泥采用低水化热的矿渣水泥，混凝土浇筑后10h进行覆盖并开始浇水，浇水养护持续15d。
事件二：工程施工至结构4层时，该地区发生了持续2h的暴雨，并伴有短时六七级大风。风雨结束后，施工项目负责人组织有关人员对现场脚手架进行检查验收，排除隐患后恢复了施工生产。
事件三：2008年9月25日，地方建设行政主管部门检查项目施工人员三级教育情况，质询项目经理部的教育内容。施工项目负责人回答：“进行了国家和地方安全生产方针、企业安全规章制度、工地安全制度、工程可能存在的不安全因素四项内容的教育。”为此受到了地方建设行政主管部门的严厉批评。
事件四：室内地面面层施工时，对木搁栅采用沥青防腐处理，木搁栅和毛地板与墙面之间未留空隙，面层木地板与墙面之间留置了10mm缝隙。
[问题]
事件一中，底板混凝土的养护开始与持续时间是否正确?说明理由。
1.公路通车年建设成本为：沥青混凝土面层120元/m2、水泥混凝土面层85元/m2、路面基层45元/m2、路面垫层28元/m2，公路使用寿命为10年，预计沥青混凝土路面每15年大修一次，水泥混凝土路面每10年大修一次，大修费用按重新铺筑面层计算。
2.旧路面挖除费用为：A方案4.5元/m2、B方案8.0元/m2。
3.假定社会成本为：A方案500 000元/年、B方案1 000 000元/年。
4.每次大修时，将增加有关社会和经济成本：预计将减少收费收入100万元，增加燃油损耗、时间损失等社会成本200万元。
问题：(30分)
假设两个方案营运养护管理成本相等，社会折现率取5%，请从全寿命周期成本的角度，选择经济合理的方案。
The review study,"Organic Agriculture in the 21st Century,”is featured as the cover story for theFebruary issue of the journal Nature Plants. It is the first to compare organic and conventional agricultureacross the main goals of sustainability identified by the National Academy of Sciences: productivity,economics，and environment.
Critics have long argued that organic agriculture is inefficient，requiring more land to yield the sameamount of food. It's true that organic farming produces lower yields，averaging 10 to 20 percent less thanconventional. Advocates contend that the environmental advantages of organic agriculture far outweighthe lower yields，and that increasing research and breeding resources for organic systems would reduce theyield gap.Sometimes excluded from these arguments is the fact that we already produce enough food tomore than feed the world's 7.4 billion people but do not provide adequate access to all individuals
In some cases，organic yields can be higher than conventional. For example，in severe droughtconditions，which are expected to increase with climate change in many areas，organic farms can produceas good，if not better，yields because of the higher water-holding capacity of organically farmed soils.
What science does tell us is that mainstream conventional farming systems have provided growingsupplies of food and other products but often at the expense of other sustainability goals.
Conventional agriculture may produce more food，but it often comes at a cost to the environment.Biodiversity loss，environmental degradation，and severe impacts on ecosystem services have not onlyaccompanied conventional farming systems but have often extended well beyond their field boundaries.With organic agriculture，environmental costs tend to be lower and the benefits greater.
Overall，organic farms tend to store more soil carbon，have better soil quality， and reduce soil erosioncompared to their conventional counterparts. Organic agriculture also creates less soil and water pollutionand lower greenhouse gas emissions. And it's more energy-efficient because it doesn't rely on syntheticfertilizers or pesticides.
Organic agriculture is also associated with greater biodiversity of plants，animals，insects andmicroorganisms as well as genetic diversity. Biodiversity increases the services that nature provides andimproves the ability of farming systems to adapt to changing conditions.
Despite lower yields，organic agriculture is more profitable for farmers because consumers are willingto pay more.Higher prices，called price premiums，can be justified as a way to compensate farmers forproviding ecosystem services and avoiding environmental damage or external costs.
51. What do we learn from the conclusion of the author's review study?
A)More resources should be tapped for feeding the world's population.
B)Organic farming may be exploited to solve the global food problem.
C)The long-term prospects of organic farming are yet to be explored.
D) Organic farming is at least as promising as conventional farming.
52. What is the critics' argument against organic farming?
A)It cannot meet the need for food.
B) It cannot increase farm yields.
C )It is not really practical.
D) It is not that productive.
53. What does the author think should be taken into account in arguing about organic farming?
A)Growth in world population.
B)Deterioration in soil fertility.
C) Inequality in food distribution.
D)Advance in farming technology.
54. What does science tell us about conventional farming?
A) It will not be able to meet global food demand.
B)It is not conducive to sustainable development.
C) It will eventually give way to organic farming.
D) It is going mainstream throughout the world.
55. Why does the author think higher prices of organic farm produce are justifiable?
A)They give farmers going organic a big competitive edge.
B)They motivate farmers to upgrade farming technology.
C) Organic farming costs more than conventional farming.
D)Organic farming does long-term good to the ecosystem.
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