题目内容
You can tell the age of a tree by counting its ring. But these records of a tree’s life really say a lot more. Scientists are using tree ring to learn what’s been happening on the sun’s surface for the last ten thousand years. Each ring represents a year of growth. As the tree grows, it adds a layer to its trunk, taking up chemical elements from the air. By looking at elements in the rings from a certain years, scientists can tell what elements were in the air that year. Dr. Stevenson is analyzing one element, carbon-14, in ring from both living and dead tree. Some ring go back almost ten thousand year to the end of the Ice Age. When Stevenson followed the carbon-14 levels changed with the intensity of solar burning. You see, the sun has cycles. Sometimes it bums fiercely, and at other times it is relatively calm. During the sun’s violent periods, it throw off charged particles in fast moving streams called "solar winds". The particularly interfere with the formation of carbon-14 on earth. When there is more solar wind activity, less carbon-14 is produced. Ten thousand years of tree ring show that the carbon-14 level rises and falls about every 420 years. The scientists concluded that solar wind activity must follow the same cycle. The purpose of the scientists in studying tree ring is to ().
查看答案
搜索结果不匹配？点我反馈
更多问题
某工程项目建设单位与施工总承包单位按《建设工程施工合同(示范文本)》签订了施工承包合同，并委托某监理公司承担施工阶段的监理任务。施工总承包单位将桩基工程分包给一家专业施工单位。 开工前： 1．总监理工程师组织监理人员熟悉设计文件时发现部分图纸设计不当，即通过计算修改了该部分图纸，并直接签发给施工总承包单位； 2．在工程定位放线期间，总监理工程师又指派测量监理员复核施工总承包单位报送的原始基准点、基准线和测量控制点； 3．总监理工程师审查了分包单位直接报送的资格报审表等相关资料； 4．在合同约定开工日期前的5天，施工总承包单位书面提交了延期10天开工申请，总监理工程师不予批准。 钢筋混凝土施工过程中，监理人员发现： 1．按合同约定由建设单位负责采购的一批钢筋虽供货方提供了质量合格证，但在使用前的抽检试验中材料检验不合格； 2．在钢筋绑扎完毕后，施工总承包单位未通知监理人员检查就准备浇筑混凝土； 3．该部位施工完毕后，混凝土浇筑时留置的混凝土试块试验结果没有达到设计要求的强度。 竣工验收时： 总承包单位完成了自查、自评工作，填写了工程竣工报验单，并将全部竣工资料报送项目监理机构，申请竣工验收。总监理工程师认为施工过程中均按要求进行了验收，即签署了竣工报验单，并向建设单位提交了质量评估报告。建设单位收到监理单位提交的质量评估报告后，即将该工程正式投入使用。 问题 建设单位收到监理单位提交的质量评估报告后，即将该工程正式投入使用的做法是否正确，说明理由。
某工程项目建设单位(发包人)根据工程建设管理的需要，将该工程分成3个标段进行施工招标。分别由A、B、C 3家公司承担施工任务。通过招标建设单位将3个标段的施工监理任务委托具有专业监理甲级资质的M监理公司一家承担。M监理公司确定了总监理工程师，成立了项目监理部。监理部下设综合办公室兼管档案、合同部兼管投资和进度、质监部兼管工地实验与检测等3个业务管理部门，设立A、B、C 3个标段监理组，监理组设组长一人负责监理组监理工作，并配有相应数量的专业监理工程师及监理员。 问题 在确定了总监理工程师和监理机构之后，开展监理工作的程序是什么
Ask someone what they have done to help the environment recently and they will almost certainly mention recycling. Recycling in the home is very important of course. However, being forced to recycle often means we already have more material than we need. We are dealing with the results of that overconsumption in the greenest way possible, but it would be far better if we did not need to bring so much material home in the first place. The total amount of packaging increased by 12% between 1999 and 2005. It now makes up a third of a typical household’s waste in the UK. In many supermarkets nowadays food items are packaged twice with plastic and cardboard. Too much packaging is doing serious damage to the environment. The UK, for example, is running out of it for carrying this unnecessary waste. If such packaging is burnt, it gives off greenhouse gases which go on to cause the greenhouse effect. Recycling helps, but the process itself uses energy. The solution is not to produce such items in the first place. Food waste is a serious problem, too. Too many supermarkets encourage customers to buy more than they need. However, a few of them are coming round to the idea that this cannot continue, encouraging customers to reuse their plastic bags, for example. But this is not just about supermarkets. It is about all of us. We have learned to associate packaging with quality. We have learned to think that something unpackaged is of poor quality. This is especially true of food. But it is also applied to a wide range of consumer products, which often have far more packaging than necessary. There are signs of hope. As more Of us recycle, we are beginning to realize just how much unnecessary materials are collecting. We need to face the wastefulness of our consumer culture, but we have a mountain to climb. What can be inferred from Paragraph 4
(三) 某电梯安装工程项目，由于电梯工程在高且深的井道内作业，每层在层门安装前留下较大的门洞，这对作业人员或其他闲杂人员存在高空坠落的危险，针对这一情况，施工项目经理部对从事影响工程产品质量的所有人员进行了控制。 施工项目经理部对该电梯工程的施工程序和施工安全技术措施的制定如下： (1)机房通向井道的预留孔随时开通以方便施工； (2)井道安装好导轨后放基准线进行配管配线； (3)层门洞靠井道壁外侧设置坚固的围封，围封的高度不小于0.8m； (4)由制造厂组装完成经调试合格后加以封记的机电协调动作部件在施工时应拆封调整后安装； (5)电梯安装单位安装完毕自检试运行结束后，由监理单位负责进行校验和调试； (6)电梯经校验和调试符合要求后，向当地特种设备安全监督部门报验要求监督检验。 施工项目经理部对施工人员主要从哪些环节进行控制
微信支付 
支付宝支付