高一英语同步练习：必修3Unit4Astronomy:thescienceofthestars第3课时Grammar基础练习一.语法知识：主语从句：做主语用的名词性从句，因其在复合句中做主语，又称主语从句，引导主语从句的有从属连词that,whether，连接代词who,what,which，连接副词when,where,how,why等。1..连接词：1）从属连词：that，whether等.that引导主语从句只起引导作用，本身无实际意义，在主语从句中不充当任何成分，但不能省略。Thatshelefthimcuthimtotheheart.Thathewillcomeiscertain由whether及其他连词引导的主语从句放在句首，句后都可。Whetheritwillpleasethemisnoteasytosay.Whethershe’scomingornotdoesn’tmattertoomuch.2)连接代词who，what，which,whatever,whichever,whoeverWhatseemseasytosomepeopleseemsdifficulttoothers.Whichsidewillwinisnotclear.3)连接副词when，where，how，why等。Whyhediditremainsamystery.Whentheywillstartisnotknownyet.Howhebecameagreatscientistisknowntousall.2.位置：主语从句可以前置，也可以后置。用it做形式主语，而把主语从句放在句末，常用下面几种句型。1）It+be+表语+主语从句1表语：（名词,形容词,过去分词）Itisapitythatwecan’tgo.Itisnosurprisethatourteamshouldhavewonthegame.ItisanhonourthatIwasinvitedtoattendthemeeting.Itiscertainthatshewilldowellinherexam.ItistruethatItoldhereverything.ItissaidthatMr.GreenhasarrivedinBeijing.ItisreportedthatChinahassentanothermanmadeearthsatelliteintoorbit.2）It+不及物动词或短语+主语从句Itseemed(happened,doesn’tmatter,hasturnedout)that…Ithappensthattheywereabsent.ItseemsthatAliceisnotcomingtothepartyatall.Itdoesn’tmatterwhethershewillcomeornot.Itmakesnodifferencewhereweshallhavethemeeting.3)It+及物动词（被动语态）+主语从句IthasbeendecidedthattheexhibitionwillnotopenonSundays.注意:1）主语从句在句首时，必须由连接词引导，不能省略这些连接词；但是如果用it做形式主语，而把主语从句放在句末时，从属连词that可以省略。误：Theyshouldlikeeachotherisnatural.正：Thattheyshouldlikeeachotherisnatural.正：Itisnaturalthattheyshouldlikeeachother.2)如果主语从句放在句首，不能用if引导，但是如果用it做形式主语，而把主语从句放在句末时，也可以用if引导.误：IfMaryreallyheardhimisreallydoubtful.正...
