Question

wheather.when的用法

Answer 1

whether的用法：
1.(引导名词从句)是否Ask him whether he can come or not.问问他是否能来.I don't know whether you like flowers,sir.先生,我不知道您是否喜欢花.
2.(与or连用,引导状语从句)不管(是)We'll go on with the work,whether we can find the necessary tools or not.不管我们能否找到所需的工具,我们要把这件工作做下去.在引导定语从句时,一般情况下whether和if都可使用,但whether的适用范围要比if广,实在不知道应用什么的时候,选whether.例如从句若出现了选择项：A or B,只能用whether而不能用if但要注意,从句为否定句时,只能用if,而不能用whether when副词adv.什么时候（用于时间的表达方式之后）在那时,其时
3.其时；当时；当场连接词conj.引导时间状语时,翻译为：当……时候,如：Don’t be afraid of asking for help when it is needed.类似并列连词,翻译为：在那时,常用于be about to do...when,hardly...when等句型中.如：We were swimming in the lake when suddenly the storm started.表原因,翻译为：既然,.如：Why do you want a new job when you’ve got such a good one already?连接副词,用于名词性从句中.如：I remember when this used to be a quiet village.（此句为宾语从句）关系副词,用于定语从句中.如：The film brought the hours back to me when I was taken good care of in that far-away village.表让步,翻译为：即使,.如：The enemy held out when they must have known there was no hope.代词pron.什么时候那时

Answer 2

具体你可以参考这一段。
when，while，as引导时间状语从句的区别
when，while，as显然都可以引导时间状语从句，但用法区别非常大。
一、when可以和延续性动词连用，也可以和短暂性动词连用；而while和as只能和延续性动词连用。
① Why do you want a new job when youve got such a good one already？（get为短暂性动词）你已经找到如此好的工作，为何还想再找新的？
②Sorry，I was out when you called me．（call为短暂性动词）对不起，你打电话时我刚好外出了。
③Strike while the iron is hot．（is为延续性动词，表示一种持续的状态）趁热打铁。
④ The students took notes as they listened．（listen为延续性动词）学生们边听课边做笔记。
二、when从句的谓语动词可以在主句谓语动作之前、之后或同时发生；while和as从句的谓语动作必须是和主句谓语动作同时发生。
1．从句动作在主句动作前发生，只用 when。
①When he had finished his homework，he took a short rest．（finished先发生）当他完成作业后，他休息了一会儿。
②When I got to the airport，the guests had left．（got to后发生）当我赶到飞机场时，客人们已经离开了。
2．从句动作和主句动作同时发生，且从句动作为延续性动词时，when，while，as都可使用。
①When ／While ／As we were dancing，a stranger came in．（dance为延续性动词）当我们跳舞时，一位陌生人走了进来。
②When ／While ／As she was making a phonecall，I was writing a letter．（make为延续性动词）当她在打电话时，我正在写信。
3．当主句、从句动作同时进行，从句动作的时间概念淡化，而主要表示主句动作发生的背景或条件时，只能用 as。这时，as常表示“随着……”；“一边……，一边……”之意。
① As the time went on，the weather got worse．（as表示“随着……”之意）
② The atmosphere gets thinner and thinner as the height increases．随着高度的增加，大气越来越稀薄。
③As years go by，China is getting stronger and richer．随着时间一年一年过去，中国变得越来越富强了。
④The little girls sang as they went．小姑娘们一边走，一边唱。
⑤The sad mother sat on the roadside，shouting as she was crying．伤心的妈妈坐在路边，边哭边叫。
4．在将来时从句中，常用when，且从句须用一般时代替将来时。
①You shall borrow the book when I have finished reading it．在我读完这本书后，你可以借阅。
②When the manager comes here for a visit next week，Ill talk with him about this．下周，经理来这参观时，我会和他谈谈此事。
三、when用于表示“一……就……”的句型中（指过去的事情）。
sb．had hardly（＝scarcely） done sth．when．．．＝Hardly ／ Scarcely had sb．done sth．when．．．
①I had hardly ／scarcely closed my eyes when someone knocked at the door．＝Hardly ／ Scarcely had I closed my eyes when someone knocked at the door．我刚一闭上眼，就有人在敲门了。
②I had hardly ／scarcely entered my room when the telephone rang．＝Hardly ／Scarcely had I entered my room when the telephone rang．我刚一走进房门，电话就响了。

Answer 3

whether表示是否怎样
后面常跟 WHEATHER... OR NOT的用法
不能单独使用

WHEN可以用在句首，表示当....的时候
也可以做时间状语