根据以下场景，回答下列问题

A公司是一家处在工业园区内的危险化学品生产经营企业。生产装置区内主要有20万t/a氯威生产装置、1.5万t/农药生产装置、4万t/邻甲苯胺生产装置和2万t/环氧，氯丙烷生产装置，氨碱装置区内有单个设计量60t液氨储罐5个，布置在密闭库房内，构成危险化学品重大危险源，库房安装有远传在线监控系统，液氯储罐配备了安全仪表监控系统。电解生产的氢气依托可燃气体公用管道进行输送。农药生产装置有原药、成品和制剂单元，主要的生产原料（外购）有三氯化磷（液体）、氰化钠（固体）、氯乙酸（固体)、2.4D酸（固体）等，分别按要求储存在相应的库房内。环氧氯丙烷生产装置主要原料为丙烷（液化烃）及氯气（自供），原料丙烷储存在单个设计量80m³的2个全压力式储罐内。建设初期生产工艺是丙烷高温氨化法，由于生产原料成本和亏损等原因，公司经过研究决定将丙烷高温氯化法生产工艺进行调整，变更为甘油法生产工艺，装置的丙烷罐区设有移动式消防冷却用水，并按要求配备了灭火器。

某安装公司中标一科研办公楼（寒冷地区）机电专业分包工程项目，承包范围包括建筑给排水及供暖系统、通风空调系统和电气系统；建筑智能化系统由建设单位发包给某智能化公司。工程合同中明确要求机电专业分包商须配合建设单位获得绿色建筑二星级评价的认证。
项目开工后，各专业设计师进行了图纸交底建设单位组织进行了图纸会审，安装公司据此展开图纸深化设计，包括各类机电管道吊装安装详图的设计及计算并通过了设计的审核批准，下图1是部分机电管道吊装安装节点详图。

【背景资料】

某地区新建一座大型自来水厂，主要单位工程有沉淀池、过滤池、消毒池等，整个工程由W建筑公司中标施工。其中沉淀池为无盖圆形池，直径40m，基础为现浇混凝土结构，厚500mm，该基础由四周向中心呈漏斗型，其高点顶面标高22.50m，低点顶面标高22.10m；池壁采用预制板拼装外缠绕预应力钢丝结构，强度等级为C40。沉淀池现况原地下水位标高26.50m。

Emerging in the late Sixties and reaching a peak in the Seventies, Land Art was one of a range of new forms, including Body Art, Performance Art, Action Art and Installation Art, which pushed art beyond the traditional confines of the studio and gallery. Rather than portraying landscape, land artists used the physical substance of the land itself as their medium.

The message of this survey of the British land art--the most comprehensive to date--is that the British variant, typified by Richard Long’s piece, was not only more domestically scaled, but a lot quirkier than its American counterpart. Indeed, while you might assume that an exhibition of Land Art would consist only of records of works rather than the works themselves, Long’s photograph of his work is the work. Since his “action” is in the past, the photograph is its sole embodiment.

That might seem rather an obscure point, but it sets the tone for an exhibition that contains a lot of black-and-white photographs and relatively few natural objects.

Long is Britain’s best-known Land Artist and his Stone Circle, a perfect ring of purplish rocks from Portishead beach laid out on the gallery floor, represents the elegant, rarefied side of the form. The Boyle Family, on the other hand, stand for its dirty, urban aspect. Comprising artists Mark Boyle and Joan Hills and their children, they recreated random sections of the British landscape on gallery walls. Their Olaf Street Study, a square of brick-strewn waste ground, is one of the few works here to embrace the commonplaceness that characterises most of our experience of the landscape most of the time.

Parks feature, particularly in the earlier works, such as John Hilliard’s very funny Across the Park, in which a long-haired stroller is variously smiled at by a pretty girl and unwittingly assaulted in a sequence of images that turn out to be different parts of the same photograph.

Generally however British land artists preferred to get away from towns, gravitating towards landscapes that are traditionally considered beautiful such as the Lake District or the Wiltshire Downs. While it probably wasn’t apparent at the time, much of this work is permeated by a spirit of romantic escapism that the likes of Wordsworth would have readily understood. Derek Jarman’s yellow-tinted film Towards Avebury, a collection of long, mostly still shots of the Wiltshire landscape, evokes a tradition of English landscape painting stretching from Samuel Palmer to Paul Nash.

In the case of Hamish Fulton, you can’t help feeling that the Scottish artist has simply found a way of making his love of walking pay. A typical work, such as Seven Days, consists of a single beautiful black-and-white photograph taken on an epic walk, with the mileage and number of days taken listed beneath. British Land Art as shown in this well selected, but relatively modestly scaled exhibition wasn’t about imposing on the landscape, more a kind of landscape-orientated light conceptual art created passing through. It had its origins in the great outdoors, but the results were as gallery-bound as the paintings of Turner and Constable.

案例四

【背景资料】

某污水厂升级改造工程，由活性炭滤池、臭氧深度处理池和泵房等构筑物组成，承包单位以6500万元中标。施工基坑围护结构为灌注桩，基底标高为-6.50m（地面标高为±0.00），基底以粉砂土层、砂卵石层为主，渗透系数较大(20～200m/d)，且北邻排水干渠，地下水位标高为-3.00m；干渠最高水位为-1.00m。

项目部组建后，依据实施性施工方案和公司下达的成本目标，测算工程人工费、材料费、施工机械费、措施费等项费用；并制定了施工成本控制措施，材料成本控制重点放在控制主材价格和限额领料方面；鉴于工地与项目部在一起，管理费一起核算。

甲向乙购买了一批价值 10 万元的货物，但签发汇票时把金额错写成 100 万元，后乙又将该票据背书给丙，当丙请求付款时，付款人拒绝付款。下列说法正确的是 ( )。

【背景资料】某市调水泵站工程，从河道取水向城区补水，以改善城区水环境，主要建设内容包括泵站主体建筑、压力箱涵、进水水池、翼墙、河道防护及闸门启闭机设备等。发包人与承包人依据《水利水电工程标准施工招标文件（2009年版）》签订了施工合同，合同工期为220天。经总监理工程师批准的施工总进度计划如图15所示，各项工作均按最早开始时间安排且匀速施工。

   事件：
事件1：承包人发现施工现场地质情况与施工图设计不符，设计变更导致工作D和工作E分别推迟10天和5天开始，造成承包人窝工损失15万元。承包人向项目监理机构提出延长工期增加费用15万元的要求。
事件2：工程开工后第90天末，监理工程师检查实际进度情况为：工作G正常，工作H提前10天，工作I延误10天。
事件3：针对事件2，发包人要求工程按合同工期完成，承包人对施工总进度计划进行了调整，压缩工作N的持续时间，并提交了赶工计划。

基础教育课程改革将综合实践活动课程确定为选修课程。

【背景资料】某精装修交付保障房工程，共12层，建筑面积5万平方米，结构形式为装配式混凝土结构。施工单位遵循“四节一环保”理念进行绿色施工管理，在施工组织设计中增加了专门的绿色施工章节，表3是部分绿色施工管理量化指标。

施工中发现作业人员有以下行为：电梯井道施工人员作业时，为施工方便，擅自临时拆除了电梯井口防护门，作业完成后恢复了防护门；进行十层预制外墙板吊装时，在没有设置安全隔离层的情况下，抹灰工人在正下方进行一层外墙面饰面作业。
施工单位在二层以上设置了悬挑长度为6m的卸料平台，卸料平台与外围护脚手架采用拉结连接，监理工程师判定为高处作业重大事故隐患。
经检查，施工单位在建筑内部装修工程的防火施工过程中（包括隐蔽工程的施工过程中及完工后）的抽样检验结果和现场进行阻燃处理、喷涂、安装作业的抽样检验结果均符合设计要求。建设单位项目负责人组织施工单位项目负责人、监理工程师和设计单位项目负责人等进行了工程质量验收。
工程竣工后，统计得到固体废弃物（不包括工程渣土、工程泥浆）排放量为1500t。

背景资料：某施工队承担一锚喷支护巷道的施工任务。设计锚杆排距1m，每断面锚杆11根；采用树脂药卷锚固，每根锚杆采用中速和快速凝固各一卷；喷混凝土厚50mm。在对200m锚喷支护巷道中间验收时，锚杆部分的记录有以下内容：（1）树脂药卷检查：材料进场验收单一张，抽查药卷3个，合格；（2）锚杆检查：1）进场抽查单一张，抽查锚杆三根，合格；2）锚固力检查有全部合格班组检查记录，中间验收采用平均分布（间隔50m）抽查共计三根，最小值不低于设计的90％；3）与锚固力检查相同办法检查锚杆间排距离，共抽查三根，偏差小于100mm；4）锚杆孔深、锚杆方向、锚杆外露长度的检查数据均符合要求。
问题：

商法与经济法的主要区别是 (    )。