while的主从句一般都用什么时态

COULD是客气的问法,不是过去时.选IS就算可以了

What are you doing when your mother is cooking ?
同时发生

首先,中学英语时态可分为两大类：present types（一现、现进、现完、一将）；past types（一过、过进、过完、过将）.其次,主从复合句表达中应考虑“时态呼应”原则,就时间状语从句而言：1、“主将从现”,即：含时、条状从的复合句中,当主句谓动为“一将”时,从句谓动应以“一现”替代、也可用“现完”.如：Tom will have a drink of milk before he goes to bed.Tom will do his homework after he has gone over his lessons.（从句行为结束后,接着进行主句动作）2、“过去对过去”,即：当主句谓动为过去时态时,从句谓动应取用一种相应的过去时.如：Mother was cooking when I reached home yesterday.（注意：“长短行为”,即一长一短两个过去行为并存时,一般用“一过”表达较短动作,用“过进”描述较长行为）.3、“（主）现完+since+（从）一过”.如：The Smiths have lived here since they came to China.对比：It is a long time since we met last.（强调“段时间”句型：It is + 段时间 + since 从句）.

一般就是where了,可能是定语从句或地点状语从句,that all depends,不过也要小心可能在定语从句中做主语、宾语等,极罕见的了.
■补充重要的一点：与occasion类似的与where在从句中常见搭配的词有：point/stage/situation/circumstance/activity/sports等
一家之言 仅作参考~望有助于你

离If近的句子是从句,远的是主句.从句用一般现在时,主语+（don't)+动词原形.或者主语加上动词单三.（主语加上doesn't+动词原形.） 主句用一般将来时will+动词原形.即 一般将来时+if+一般现在时.
另外主过从过的虚拟条件句用过去将来时+if+一般过去式.构成是：would+动词原形+if+主语+一般过去式（主语+动词过去式）.表示根本不可能的事情.if I WERE YOU 是常见的考法.记住这些就可以了.不过这里的if全部都是“如果”的意思.另外,if还可以做“是否”讲,引导的是宾语从句.原来的句子是一般疑问句,变成宾语从句可以用if.

not until + 从句 ,+主句（部分倒装）例如：not until he came back did I finished my home work .（直到他回来我才完成作业）
至于时态就要根据实际的句子在能决定,没有说一定用什么时态的

1、while 引导的时间状语从句,从句通常用过去进行时,主句用过去进行时.且while从句中的谓语动词必须是持续动词.
2、而when从句通常与一般过去时,一般现在时连用,且从句的谓语动词多是非延续性动词,但是也可以是延续性动词.

主语用现在完成时,从句一般过去时
We've been friends ever since we left school.
我们在学校毕业后一直是朋友.
I've been engaged in this kind of work ever since I graduated from the university in 1990.
我自从1990年毕业以来就一直从事这项工作.
不懂追问*^__^*

整句大结构 分析 首先是if引导的条件状语从句.
(If you're scheduled for an interview at a company you've never visited and aren't sure what to wear) 条件状语从句,（send for a copy of its annual report and study what the employees pictured are wearing,or drop by ahead of time to see how they dress）（祈使句,是主句,主语you省略）
局部结构 If you are scheduled for an interview at a company you've never visited and aren't sure what to wear, (and前后两个并列谓语项,或系表结构,即 are scheduled for an interview at a company you've never visited 和aren't sure what to wear 共用主语you） ；
a company you've never visited (这部分 you've never visited 是定语从句,省略了关系代词that,修饰前面的company; 而aren't sure what to wear,这里的what to wear 是疑问词加不定时作为aren't sure 的宾语.
局部结构 send for a copy of its annual report and study what the employees pictured are wearing,与 drop by ahead of time to see how they dress有or连接两个并列句,构成并列句；
send for a copy of its annual report 与 study what the employees pictured are wearing,又是有and连接的两个并列单句,说明or连接的前面一句 自己本身又是并列句.
study what the employees pictured are wearing 这部分里what the employees pictured are wearing 是study的宾语从句,里面的pictured 是过去分词作后置定语修饰employees

.

主句是 Don't talk,是一个个祈使句
while you are eating 作状语,因为 eating 是一个持续性动作
在 eating Don't talk 这个动作会一直延续
直到 eating 结束

if有两大用法,一个是译为一般的如果,一个是用作假设的如果
在 if 引导的条件状语从句中,如果从句谈论的是一个推测将来有可能发生的事实,主句用一般将来时态,从句用一般现在时态.一般译为如果 ,如：
if it rains tomorrow,i won't go out.
如果 if 条件句谈论的是一个主观的意愿,则主句,从句大多用一般现在时态.一般译为如果,如：
If you dont want to go out ,you can stay at home.
if还有一个最重要的用法,用于虚拟句.表示对不可能发生的事物的一种猜测或假设的语气.
"if"条件状语从句中的虚拟语气的结构如下表：
虚拟类型从句主句
对现在情况的假设一般过去时would+动词原形
对将来情况的假设一般过去时would+动词原形
对过去情况的假设过去完成时would + have + 过去分词
一、对现在情况的假设
主要表示对不可能发生或不太可能发生的现在情况的假设,例如：
if i were you ,i would not tell him.如果我是你,我不会告诉他.
二、对将来情况的假设
If I had enough time,I would certainly go.如果我有足够的时间,我一定会去
三、对过去情况的假设
if i had known this matter before,i wouldn't have done it.如果我早知道这件事,我就不会这样做了.
仅供参考

一般没有限制,唯一的限制来自语境的需求,
比如
As we are approaching the summit,through the treetops we can see the valley below and ...
As we were approaching the summit,through the treetops we could see the valley below and ...
As we approached the summit,through the treetops we could see the valley below and ...
语法上都对,
第一句现在时态通常用于现场报道,但主宾时态要一致：are approaching ...can see
第二、第三句用于叙述情景.
不可用 approaches ,这是第三人单数,只有前面是 he/she 时可用：
As he approaches ...he can see ...

I was in charge of new products testing when I was a test technician.
没必要简化.
在照顾上下文时,可以转换句式：
I was a test technician and in charge of new products testing.
I was a test technician,in charge of new products testing.
I was in charge of new products testing as a test technician.
as a test technician,I was in charge of new products testing.
was 已经表示“过去”,不要在句中再出现“过去”的翻译.

1. when 连接副词,“当.的时候”,A.引导时间状语从句.如: When he came in, Tom was sleeping.B.引导主语/表语/宾语从句.如：I don't know when he will be back. When he will come back is unknown. The que...

语意上的问题吧
先说什么事情,再说你和他们不熟

按英语习惯,当never,hardly,seldom,little,few,not until,not,no,no sooner,by no means,under no circumstances等否定词置于句首时,其后要用部分倒装.如：
Never did I see him again.后来我再也没见到过他了.
Little did I dream that the girl was my niece.我做梦也没想到那女孩是我的侄女.
Seldom does he go out for dinner.他很少出去吃饭.
Hardly does she have time to listen to music.他几乎没时间听音乐.
No sooner had we reached the airport than the plane took off.我们刚到机场,飞机就起飞了.
Not until we lose our health do we realize its value.等到失去了健康,才明白它的价值.
No sooner had she agreed to marry him than she started to have terrible doubts.她刚同意嫁给他她就开始产生可怕的疑虑.
Under no circumstances are children allowed in the bar.在任何情况下也不能允许儿童进酒吧.
如果你是指no sooner ...than...和 hardly...when...的话 则no sooner和hardly 后倒装 且时态退一格 than 和 when后不到装

语调这东西不是看会的,是听会的,就算你知道了哪里升哪里降你也不可能真正读准.比如Good morning就有N个调,N个不一样的意思,这可不是文字上学得好的.

你的句子是正确的
只要主要子句的动词不是过去式,也不是过去完成式,那麼附属子句的动词可以是任何可以正确表达意思的时态.然而,如果主要子句的动词是过去式或过去完成式,那麼附属子句的动词就必须是过去式或过去完成式.这个规则的例外是,附属子句是在表达众所周知的普遍事实和真理：
In the 1950s,English teachers still believed that a background in Latin is essential for an understanding of English.
Columbus somehow knew that the world is round.
Slaveowners widely understood that literacy among oppressed people is a dangerous thing.http://www.cybertranslator.idv.tw/grammar/sequence.htm看下这个网站

学习" if " 引导的条件状语从句的用法,现在总结一下:
if 条件句不一般,几个要点记心间;
条件句,放在前,逗号要放句中间.
条件句表可能,主句多用将来时；
条件句表事实,主句常用现在时.
在 if 引导的条件状语从句中,如果从句谈论的是一个有可能发生的事实及其产生的相关的结果,主句用一般将来时态,从句用一般现在时态.如：
We can walk there if we can't find a bus .
If it rains tomorrow ,we will not go to the zoo.
What will you do if you find a panda in danger.
如果 if 条件句谈论的是重复发生和预示要发生的情景和事件,则主从句大多用一般现在时态.如：
If bears are in danger ,they attack people.
注意 ：
在 if 引导的条件状语从句中,if 和条件句位置灵活,可直接放在主句后面,若 if 条件句放句首,
从句后面要加逗号,和主句隔开.
还要注意前后时态一致原则

此句翻译为：他认为他没有错.
“not”实际上否定的是从句中的“think”,但这类从句否定式会迁移到主句中.
这种现象在英语中叫做“否定的迁移”(negative transition）.
这样的词主要是：think, believe, suppose, guess, imagine等
eg：我相信他明天不会来了.
错句：I believe he will not come tomorrow.
正确：I don't believe he will come tomorrow
希望对你有帮助 =.=

看情况了,一般情况下是这样
有种例外,如故你think的是一种客观事实,如地球绕着太阳转,那么就要用一般现在时

when 引导的是从句主句是一般将来时，从句为一般现在时；主句是现在进行时，从句为一般现在时；主句是一般过去时，从句为一般过去时；主句是过去进行时，从句为一般过去时；主句是过去完成时，从句为一般过去时。when 有个特殊用法，表转折，此时它的意思是“这时”...

一般来说 主句和从句是时态一致的 至于延续和非延续的动词可以给出具体的例子么?

would rather：与过去事实相反用过去完成时,与现在事实相反用过去时.it's (high) time 后用一般过去时或should+动词原形,should可省略.

第一,“虚拟语气,若主从句主语一致,且谓语部分包含有动词be,通常可将主语和动词be省略”其实,这个不仅仅局限于虚拟从句和由if引导的条件状语从句,还有有很多状语从句（非虚拟语气）也适合.比如：I'll also provide a...