v．­ing形式作主语[观察例句]观察下列句子，指出黑体部分在句中的语法作用。1．Sincethen，findingwaystogrowmorericehasbeenhislifegoal.动词­ing短语作主语2．Spendingmoneyonhimselforleadingacomfortablelifealsomeansverylittletohim.动词­ing短语作主语3．Justdreamingforthings，however，costsnothing.动词­ing短语作主语4．Mary'sbeinglateforclassmadeherteacherangry.动词­ing的复合结构作主语5．Itisnousearguingwithhimaboutsuchamatter.动词­ing短语作真正主语[归纳用法]一、动词­ing作主语的用法1．动词­ing形式作主语时具有名词的特征，谓语动词一般用单数。Drinkingalotofwaterisgoodforyou.多喝水对你有好处。GoingtoHangzhoubytraintakesabout16hoursfromhere.从这儿乘火车到杭州大约要(花费)16个小时。2．用it作形式主语，而将动词­ing形式的动词或动词短语放到句末，以避免句子结构头重脚轻。常见句型有：Itis＋nogood(nouse，fun，apleasure，awasteoftime)＋doing...。Itisnogoodeatingtoomuchsweetfood.吃太多的甜食没有好处。Itisawasteoftimesittingherewithoutdoinganything.在这儿干坐着是浪费时间。二、动词­ing的复合结构作主语作主语的动词­ing的复合结构通常由“形容词性物主代词/名词所有格＋动词­ing”构成，其中的形容词性物主代词或名词所有格是动词­ing的逻辑主语。Hisreturningbacktoworkisagreathelptous.他回来工作对我们来说是一大帮助。It'snouseMary'spretendingthatshedidn'tknowtherules.玛丽假装不了解这些规章，这没有意义。[即学即练1]单句语法填空①Their(they)comingwasagreatencouragementtous.②Reading(read)Englishaloudinthemorningwilldoyoualotofgood.③It'snousecomplaining(complain)withouttakinganyaction.④It'sawasteoftimetrying(try)topersuadesuchaperson.三、动词­ing形式和不定式作主语的区别动词­ing形式作主语表示一般的、非一次的、抽象的、泛指的动作；不定式作主语常表示具体的、某一次的、特定的动作。Swimmingisoneofmyfavouritesports.游泳是我喜爱的运动之一。(泛指)Toswiminthislakeisverydangerous.在这个湖里游泳很危险。(特指)[名师点津]用动词­ing形式或不定式作主语时，要注意主语和表语的一致。即当表语是动词­ing形式时，主语也要用动词­ing形式，当表语是不定式时，主语也要用不定式。Respectingothersisrespectingoneself./Torespectothersistorespectoneself.尊重别人就是尊重自己。[即学即练2]单句语法填空①Playing(play)withfireisdangerous.②Tofinish(finish)theworkintenminutesisveryhard.③Swimmingisgoodforhealth，buttoswiminsuchapollutedriverisharmfultohealth.(swim)④Climbingmountainsis(be)reallydifficultfortheold.Ⅰ.单句语法填空1．It'snousewaiting(wait)here.Let'swalkhome.2．Swimmingwithdolphinsis(be)oneoftheworld'smostprofitabletouristactivities.3．Tosee(see)istobelieve.4．Toread(read)thisarticlewillmakemethinkofmyhometown.5．Asking(ask)awom