if和whether在名词性从句中的用法(课堂PPT).ppt

单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,if,和,whether,在名词性从句,中的用法,1,whether,和,if,都可以用作连词，引导名词性从句，表示“是否”。不同的是,whether,可以引导所有类型的名词性从句；而,if,只能引导宾语从句和主语从句。,2,宾语从句,引导宾语从句既可以用,whether,，也可以用,if,，两者常可以互换。,whether,从正反两个方面提出疑问，选择意义较强，多用于正式文体中；而,if,多用于口语，比较强调单方面，如：,He asked me whether/if I could lend him my bike.,Could you tell us whether/if it snows in winter in Australia?,She asked them whether/if they had gone there by car or by train.,3,1.,在介词后引导宾语从句只用,whether,。,This depends on whether we are determined to do it.,I am not interested in whether youll come or not.,Im thinking about whether well have a meeting.,4,点例外,4,2.,在及物,动词,discuss,，,consider,等,后的宾语从句中，只能用,whether,。,We discussed whether we should make a change in our plan.,We were discussing whether we should take some measures.,Were discussing whether well go on a picnic.,5,3.,宾语从句放在句首表示强调时，只能用,whether,。,Whether it is true or not,I cant tell.,Whether you have met George before,I cant remember.,6,4.,引导一个否定的宾语从句，,只用,if,。,whether,不能用来引导否定的宾语从句，因为它表示正反两方面的选择意义比较强。,She asked me if Tom didnt come.,He considered if he shouldnt tell her the secret.,7,whether/if,引导宾语从句,通常可以互换（,4,点例外）,只用,whether,discuss,等后,引导宾语从句放句首表强调,只用,if,：,介词后,引导否定的宾语从句,8,1,I d like to invite you to a party this evening.,Thank you,but _ Ill be free I m not sure at the moment.,A.while B.if,C.when,2,-What are you anxious about?,-_,A.If we succeed,B.That we can succeed,C.Do we succeed,D.Whether we can succeed,3.At the meeting,we discussed _ we should employ more workers.,A.if ,C.that D.,不填,D.whether,B.whether,9,主语从句,注意：,whether,和,if,均可引导主语从句，但,if,引导的从句不能位于句首。,引导主语从句,并在句首时,只用,whether,。,Whether we go there is not decided.,Its doubtful whether/if therell be any seats left.,10,引导表语从句时只用,whether,。,What we want to know is whether he will come to speak to us tomorrow.,The doubt was whether you had broken the beautiful vase.,The question is whether we can get there on time.,表语从句,11,引导同位语从句时只用,whether,。,The question whether well build another lecture building hasnt been settled.,The question whether hell come is unknown.,We must consider the question whether we will take these measures.,同位语从句,12,Exercises,1.The question has not been answered _ Taiwan will be included on the Olympic torch relay route.,A,that,C,which D,if,2._ theyll go to the Summer Palace _ the weather.,A.If;depends on,B.Whether;depends upon,C.Whether;depended on,D.If;depended upon,B,whether,13,1.,直接与,or not,连用时只用,whether,。,I dont know whether or not he will go.,Im not sure whether or not they will come for our help.,【注意】,若,whether,和,or not,不连在一起，在,口,语中可以用,if,取代,whether,。例如：,I am not certain whether/if the train will arrive on time or not.,I dont care whether/if your car breaks down or not.,其他情况（,3,点）,14,2.,在动词不定式之前，只能用,whether,。,He doesnt know whether to stay or not.,She doesnt knows whether to get married now or wait.,15,3.,当用,if,会引起歧义时只用,whether,。,if,除引导宾语从句外，还可以引导条件状语从句，作“,如果,”解,。,Please let me know if you intend to come.,A,：,if,引导宾语从句,“请让我知道你是否想来。”,B,：,if,引导条件状语从句,“如果你打算来，请让我知道。”,Please let me know whether you intend to come.,EX:,Let me know if he has left for Shanghai.,请告诉我他是否已经去上海了。,如果他,已经,去上海,了,，请告诉我一声。,Let me know whether he has left for Shanghai.,16,Summary,宾语从句（,4,点）,discuss,等后,whether,宾语从句放句首表强调,whether,引导否定宾语从句用,if,主语从句：,表语从句：,同位语从句：,其他：,不定式前用,whether,if,有歧义时用,whether,引导名词性从句,介词后用,whether,置于句首用,whether,whether,whethe,r,whether or not,连用,17,Thank you,18,