请简述Python中类对象与实例对象、类属性与实例属性各自的区别?并简述它们各自的用途。
交叉网线两端的线序是怎样的?
煤与瓦斯突出有什么预兆?
测试文档有哪些作用?
背景资料：
某写字楼工程，地下1层，地上15层，框架剪力墙结构。首层中厅高12米，施工单位的项目部编制的模板支架施工方案是满堂扣件式钢管脚手架，方案由项目部技术负责人审批后实施。施工中，某工人在中厅高空搭设脚手架时随手将扳白手放在脚手架上，脚手架受振动后扳手从上面滑落，顺着楼板预留洞口(平面尺寸0.25m×0.50m)砸到在地下室施工的王姓工人头部。由于王姓工人认为在室内的楼板下作业没有危险，故没有戴安全帽，被砸成重伤。
问题：
1.分析该起安全事故的原因。
2.写出该模板支架施工方案正确的审批程序。
3.扳手放在脚手架上是否正确?说明理由。
4.何谓“三宝”和“四口”?本例的预留洞口应如何防护?
Directions:
Inthissection,thereare10incompletesentences.Youarerequiredtocompleteeachonebydecidingonthemostappropriatewordorwordsfromthe4choicesmarkedA,B,CandD.ThenyoushouldmarkthecorrespondingletterontheAnswerSheetwithasinglelinethroughthecenter.
21、62%ofthepeoplesurveyedsaidtheyalwaysavoided______theirsmartphonesduringmeals.
A.useB.usingC.touseD.used
22、TheHRdepartmentisacriticalpartofemployeewell-beinginanybusiness,nomatter______smallitis.
A.howB.whatC.whereD.which
23、Accordingtotheregulation,inspections______toensurethatthesystemsareingoodcondition.
A.demandedB.havedemandedC.bedemandedD.aredemanded
24、Beforeyouthinkaboutaskingforapromotion,makesurethateitherapositionopeningexists______anewpositionisneededtobecreated.
A.andB.norC.orD.but
25、ThetrafficwasmakingsomuchnoisethatIcouldn'thearwhathe______.
A.issayingB.wassayingC.hassaidD.willsay
26、Ourcompanycultureis______makesussuccessfulincreatingafriendlyandexcitingenvironment.
A.whereB.howC.whatD.why
27、Mostpeopleweregreatlyshockedbythenews______theITcompanyhadgonebankrupt.
A.whatB.howC.whyD.that
28、IwouldprobablytrytofindabetterjobifI______inyourposition.
A.amB.wereC.havebeenD.be
29、Ifyouare______busytoattendthemeeting,youcansendyourassistanttotakeyourplace.
A.veryB.soC.tooD.more
30、Ihadtowaitforanothertwomonthstobeabletohavethecar______.
A.fixingB.fixC.tofixD.fixed
背景：
某综合商务大厦为框架—剪力墙结构，是一座现代化的智能型建筑，设计使用年限50年。该箭镞地下3层，地上28层，建筑面积5.8万平方米。该工程2007年8月10日主题结构验收合格，2008年3月20日施工单位提交竣工验收报告，2008年4月2日竣工验收合格。
问题：
1、该工程建设工程承包单位应何时提交质量保修书?
2、该工程质量保修书应明确哪些内容?在正常使用条件下，建设工程的最低保修年限为多少?
3、写出本单位工程各分项的保修期具体起止日期?
阐述城域网三层交换机与千兆比交换路由器(GSR)之间的区别。
Directions:
Thissectionistotestyourabilitytocomprehendshortpassages.Youwillheararecordedpassage.Afterthatyouwillhearfivequestions.Boththepassageandthequestionswillbereadtwotimes.Whenyouhearaquestion,youshouldcompletetheanswertoitwithawordorashortmphrase(innomorethan3words).Thequestionsandincompleteanswersareprintedinyourtestpaper.YoushouldwriteyouranswersontheAnswerSheetcorrespondingly.
16、Whatproductdoesthecompanyproduce?______.
17、Whenwasthecompanysetup?______ago.
18、Wherearetheirproductssold?Both______andabroad.
19、Accordingtothespeaker,whydotheirproductshaveagoodreputation?
Becauseofthehighqualityandgood______theyprovide.
20、Whatdoesthespeakerpromisetogiveforalargeorder?A______.
Directions:
Thissectionistotestyourabilitytounderstandshortdialogues.Thereare5recordeddialoguesinit.Aftereachdialogue,thereisarecordedquestion.Boththedialoguesandquestionswillbespokenonlyonce.Whenyouhearaquestion,youshoulddecideonthecorrectanswerfromthe4choicesmarkedA,B,CandDgiveninyourtestpaper.ThenyoushouldmarkthecorrespondingletterontheAnswerSheetwithasinglelinethroughthecenter.
1、A.Thereisnopaper.
B.Themancanusetheprinter.
C.Theprinterdoesn'twork.
D.Themanhastopayfirst.
2、A.Hehasgotanewjob.
B.Hehasgotapayrise.
C.Hehasbeenpromoted.
D.Hehasboughtanapartment.
3、A.Sellacar.
B.Rentacar.
C.Repairacar.
D.Buyausedcar.
4、A.Hedoesn'tlikethecolor.
B.Hedoesn'tlikethestyle.
C.Itistoosmall.
D.Itisofpoorquality.
5、A.Thechiefengineer.
B.Thereceptionist.
C.Theofficesecretary.
D.Thesalesmanager.