Unit3Unit3LanguageinuseModule4Rulesandsuggestions1.Tosummariseandconsolidatetheuseofmodalverbs2.Toknowmorerulesofeco-tourismObjectivesAreyoufamiliarwiththesesentences?Theyareallfromthismodule.1.Youmustbecarefuloffallingstones.2.Youmustn’twalktooclosetotheedgeofthehillpathbecauseyoumightfallandhurtyourselves.3.Youshouldalwayswearproperclothes.4.Bearsmightthinkourrubbishisfood.5.—Canwegorockclimbing?N’t6.Youmustn’tgooffonyourown.7.Youmayneedsomewater.8.Weshouldhangthefoodinatreetonight.9.Theycansmellfoodfromalongwayaway.10.Bearsmightthinkourrubbishisfood.11.Noonecanrunfasterintheforestthanabear.12.Youmustn’tmakeanysuddenmovesormakeasound.Andaboveall,youmustn’trun.1.You________becarefuloffallingstones.2.You________(not)walktooclosetotheedgeofthehillpathbecauseyou_______fallandhurtyourselves.3.You________alwayswearproperclothes.4.Bears________thinkourrubbishisfood.5.—______wegorockclimbing?—No,you_______(not).6.You________(not)gooffonyourown.mustmustn’tmightshouldmightCancan’tmustn’tgoReady?7.You________needsomewater.8.We________hangthefoodinatreetonight.9.They_______smellfoodfromalongwayaway.10.Bears________thinkourrubbishisfood.11.Noone________runfasterintheforestthanabear.12.You________(not)makeanysuddenmovesormakeasound.Andaboveall,you_________(not)run.mayshouldcanmightcanmustn’tmustn’t情态动词本身有一定的意义，但不能独立作谓语，只能与其后的动词原形一起构成谓语，表示说话人的情绪、态度或语气，用来表达建议、请求、可能或意愿等。情态动词没有人称和数的变化，情态动词后必须跟动词原形。常见的情态动词有：can,could,may,might,must,need,shall,will,should,would。情态动词Canyouliftthisheavybox?(体力)Marycanspeakthreelanguages.(知识)Canyouskate?(技能)此时可用beableto代替。can只有一般现在时和一般过去式;而beableto则有更多的时态。①表示能力(体力,知识,技能),常用情态动词can和could表达。如：I’llnotbeabletocomethisafternoon.(一般将来时)Hewasabletogotothepartyyesterdayeveninginspiteoftheheavyrain.当表示“经过努力才得以做成功某事”时用beableto,不能用can。如：—CanIgonow?—...
