once 是什么词?都怎么用?

once 是什么词?都怎么用?
once 是什么词?都怎么用?

once 是什么词?都怎么用?
定语从句一、考点聚焦1、功能：相当于形容词,修饰名词或代词,在句中作定语2、位置：定语从句置于被修饰词之后 Those who are willing to attend the party,sign here please.3、先行词：被定语从句修饰的词称为先行词（1）先行词一般是名词和不定代词,如:some-,any-,every-和no与-boy,-thing的合成词；或all、none、any、some、that、those等代词.数词也可以作先行词,人称代词也同样可作先行词.（2）先行词与关系词是等量关系.必须注意两点：①先行词在从句中作主语时,从句谓语动词的数由先行词而定.This is the place which is worth visiting.②关系词在从句句子中充当了成分,其意思就是先行词的意义,所以在从句中不能重复其意.There are many places we can visit（them）in China.4、关系词：引导定语从句的都称关系词关系代词：who,whom,which,that,whose,as.关系副词：when,where,why.that偶尔也作关系副词.5、确定关系词的步骤（1）先找关系词,看先行词指的是什么.（2）看关系词在从句中所充当的成分.6、在定语从句中,当先行词指物时,下列情况的关系词宜用that而不用which（1）先行词被①形容词最高级 ②序数词 ③数词几种词修饰或被 ④only、any、few、little、no、all、one of等修饰时.（2）先行词为all、much、little、none、few、one、something、anything等不定代词时.（3）先行词中既有人又有物时.He was looking pleasantly at te children and parcels that filled his bus.（4）先行词在主句中作表语关系词在从句中作表语时.The village is no longer the one that was 5 years ago.（5）当主句中含有疑问词which时.Which are the books that you bought for me 7、宜用which而不用that的情况（1）在非限制性定语从句中（2）在关系词前有介词时（3）当先行词本身是that时（4）当关系词离先行词较远时8、关系词who与that指人时,也有不同情况分别用不同的关系词（1）当主句是there be句型时,关系词用who.（2）先行词是为anyone、those、someone、everyone、one等词时,关系词用who.（3）当主句是who作疑问词时,关系词用that.Who is that girl that is standing by the window?（4）whom在从句中只作宾语,可被who取代.9、whose作关系词既指人又指物,在从句中作定语.如：Do you know Mr.Smith whose story is very moving There is a room,whose window faces the river.There is a room,the window of which faces the river.10、关系代词as,在从句中作主语、宾语和表语.（1）先行词被such和the same修饰,或句型as many（much）中,从句都用as 引导.Such books as you bought are useful.The school is just the same as it was 10 years age.注意：区别①such … that … 引导的结果状语从句.They are suchlovely children that we love them much.②the same … that … 引导定语从句.I want to use the same tool that you used just now.（2）无先行词的定语从句用as和which引导.区别：①意义上：as 含有“这点正如……一样”.②位置上：as 从句可置句首,也可在另处.He didn’t pass the exam,as we had expected.There is lots of air in loose snow,which can keep the cold out.As is known,the earth is round,not flat.11、关系副词when与where、why、thatwhen 指时间 = in / at / on / during whichwhere指地点 = in / at / from / whichwhy指原因 = for which当先行词为way、day、reason、time时,可用that作关系副词.（非正式场合）I don’t like the way that / in which / he talks.当time作先行词时,关系词可以省掉.This is the first time I have given you a lesson in French.12、必须注意的问题（1）关系词作主语时,从句中谓语的数.（2）注意区别定语从句与强调句.①定语从句中关系词作从句成分,复合句.②强调it无意义,that / who不是引导词.③强调it is / was和that / who后如果句子意思讲得通则是强调句,讲不通则不是.It is the museum that / which we visited last year.(定语从句)It was in the hotel that we stayed last night.（强调句）（3）定语从句与同位语从句的区别.①定语从句引导词被称为关系词,that充当主语、宾语、表语.有时可省略.②同位语从句引导词被叫做连词,that不能充当任何成分,不可省.Word came that their army was defeated.(同位语)We expressed to them our wish that was the same as their.(定语)（4）关系词在从句中省略的情况.①关系词作宾语,前无介词时.②关系词作表语.（5）限制性定语从句与非限制性定语从句的翻译.（6）关系词前有介词或复杂介词,关系词只能是which和whom.（7）几个特殊的定语从句句型：①He is the only one of the students who has got very good marks in the match.（句中one为先行词）He is one of the students who have got good marks in the match.（句中students为先行词）②Is this place the one (that) we visited yesterday?Is this the place(that / which)we visited yesterday ③He stood at the window,from where he could see what was happening.④It may rain,in which case the match will be put off.