It作形式主语常见用法

It作形式主语常见句型1.It+be+形容词+that-从句可用于此句型的形容词有:wonderful,true，good，right，wrong，（un）important，useless，surprising，disturbing,frightening,alarming,clear，unusual，lucky，certain,necessary等。如：①Itisquitecertainthathewillbeatthemeeting.他将出席会议是无疑的。②Itissurprisingthathecamelatetoschoolthismorning.他今天早上迟到真令人惊讶。③Itisimportantthatwe(should)studyhard.我们努力学习是很重要的。注意:该句型中的形容词是（un）important,necessary等时，从句应为(should)+动词原形。Itisimportantthatwe(should)learnEnglishwell.Itisnecessarythathe(should)rememberthesewords.2.It+be+名词+that-从句适用该句型的名词（词组）有:apity，anhonor，agoodthing，afact，asurprise，aquestion,ashame,acustom,atruth,ourhope,nowonder,good/badmanners等。如：①Itisapity(that)youmissedthesportsmeetinglastweek.你错过了上周的运动会太可惜了。②ItisafactthatEnglishisbeingacceptedasaninternationallanguage.事实上英语已经被作为一种国际语言而接受了。3.It＋seem／appear／happen的适当形式＋that从句。①Itseemsthatthereisabigwastepipecomingdownfromthetown.②Itappearedthathewascalm,butinsidehisheartwasbeatingwildlywithfear.4.It+be+过去分词+主语从句，这类过去分词有：announced,believed,expected,hoped,decided,reported,said,shown等，如：Itisreportedthat16peoplewerekilledintheearthquake.Itisnotdecidedwhowillgivetheoperationtothepatient.5.Itistime(abouttime,hightime)that...该句型中that后的从句应该用虚拟语气，值得注意的是①常用过去时态表示虚拟．②有时也用should+动词原形，should不能省。常译为＂是（正是）．．．的时侯．．．＂。Itistimethatchildrenshouldgotobed.=Itistimethatchildrenwenttobed.6.Itisthefirst(second...)timethat...用完成时态。至于用什么完成时态，由主句的谓语动词的时态决定。如果是一般现在时，后面从句用现在完成时态；如果是一般过去时，后面从句则用过去完成时态。该结构中that可以省去；it有时用this替换．常译为＂是第一（二）．．．次．．．＂。ItisthefirsttimeIhavebeenhere.=ThisisthefirsttimeIhavebeenhere.7.It+be+adj./n.(forsb./ofsb.)+todosth.该句型中的形容词通常是表示事物的特点或特征的如difficult，hard，easy，impossible，necessary，important等，此时用for；或表示人的性格特征或特点的如nice，good，bad，kind，silly，foolish，wise，clever，careless，rude，brave，cruel，careful，grateful等，这时要用of。如：①Itisfoolishofyoutogiveupsuchagoodchance.②Itisnecessaryforcollegestudentstomasteratleastaforeignlanguage.