Mr Smith understands that _____ maths has always been easy f

Mr Smith understands that _____ maths has always been easy for him,it is not easy for the students.
A.while B.when
while和when作为“尽管”讲时,区别是什么?

虽然when和while都有“尽管”的意思,但是在这个句子里很明显可以看出来强调的是一种对比关系,这是while有,而when没有的功能.这句话可翻译为：尽管数学对他来说很简单,然而对一般学生来说却并不简单.这里的while即是“尽管,然而,却”的意思,强调的是对比关系.
而关于when的尽管,一般不常用,通常是意译过来,举个例子：
She stopped short when she ought to have continued.
尽管她应该继续下去,她却突然停住了.
很明显没有对比的意思.
下面的具体区别是贴过来的,可以看看,讲得还不错~
两者的区别如下：
①when是at or during the time that,既指时间点,也可指一段时间；
while是during the time that,只指一段时间,因此when引导的时间状语从句中的动词可以是终止性动词,也可以是延续性动词,而while从句中的动词必须是延续性动词.
②when 说明从句的动作和主句的动作可以是同时,也可以是先后发生；while 则强调主句的动作在从句动作的发生的过程中或主从句两个动作同时发生.
③由when引导的时间状语从句,主句用过去进行时,从句应用一般过去时；如果从句和主句的动作同时发生,两句都用过去进行时的时候,多用while引导,如：
a.When the teacher came in,we were talking.
当此句改变主从句的位置时,则为：
While we were talking,the teacher came in.
b.They were singing while we were dancing.
④when和while 还可作并列连词.when表示“在那时”；while表示“而,却”,表对照关系.如：
a.The children were running to move the bag of rice when they heard the sound of a motor bike.
孩子们正要跑过去搬开那袋米,这时他们听到了摩托车的声音.
b.He is strong while his brother is weak.
他长得很结实,而他弟弟却很瘦弱.
when; while 当……时候
while能用when代替; 但是when却不一定能用while代替.
while+从句,动作一定会延续
when+延续性动词/瞬间动词; when he arrived
when he died
when,while强调动作同时发生
过去进行时 :
在过去的某一点时间,或者是过去某一动作同时发生的另外一个动作
瞬间动词(arrive)无进行时态
I am arriving 进行时态表示将要
When he arrived,I was having dinner.
同时发生的两个动作,均用过去进行时
When I was doing my homework,my mother was cooking.
When my mother was doing the housework,my father was watching TV.
同时发生的两个动作
1.一个用一般过去时,另一个用过去进行时
2.分工的情况,均用过去进行时
When the plane arrived,...were waiting inside the main building
while others were waiting on...
While...
...were keeping guard at the door,two others opened the parcel.
表面上是分工,两个动作同时发生,不是同时开始同时结束,延续时间不一致,
长一点时间的动作用进行时态,短时间的动作用过去时.
When someone knocked at the door,I was having dinner.
when和while引导的时间状语从句与这一时态连用.所以区别when和while的用法成了这一单元的难点.（一）、when,while都有“当……时候”的意思.when既可表示某一点时间,也可以表示某一段时间 .在when引导的时间状语从句中,其谓语动词可以是延续性的,也可以是非延续性的,可与主句中的谓语动词同时发生,也可在其后发生.例如：1、I was just reading a book when she came into my room.她走进我房间时,我正在看书.2、Were you writing when the teacher came in?老师进来的时候,你在写信吗?3、When he was a child he was always trying out new ideas.他小时候就常常试验一些新的设想.（二）、while只能表示某一段时间,不能表示某一点时间.在while引导的时间状语从句中,其谓语动词只能是延续性的,而且也只能与主句中的谓语动词同时发生或存在.例如：1、While Jim was mending his bike,Lin Tao came to see him.正当吉姆修自行车时,林涛来看他.2、You can’t do your homework while you’re watching TV.你不能一边看电视一边做家庭作业.（三）、另外,when和while的区别还在于：while引导的时间状语从句多用进行时态,而when引导的时间状语从句多用一般时态.例如：1、While they were talking ,the bell rang.正在他们谈话的时候,上课铃响了.2、I was doing my homework when my mother came back home yesterday evening.昨天晚上妈妈回家的时候,我正在做家庭作业.
when/while都可做并列连词．前者表and at that time,(这时,突然),后者表对比,可译为”然而”
I was going downstairs when the telephone rang.
Lucy is in blue while Lily is in green.
when后加瞬间动词 while后也可加持续性动词