英语强调句it is ...that/who..that/who可以用when换吗

不能
被强调部分是人，可以用that或who
但被强调部分是“物”的时候，必须用that，时间可看做物，所以用that
强调句中是没有when的额

我肯定的说不可以，单选题(如果已经判断为强调句）一定不能选when，一般都选that.

我错了，是用that的when好像没看到过

可以的。比如说：
It was a fortnight ago when I realised my book mysteriously disappeared.
It was a while ago when I found out the answer to this question.
不过，当你用到“when“时，一般都是指时间，而且是过去，所以“It is”很少用到，而常是“it was”。

当然不能用"when"替换了.
什么是强调句呢?
强调句是一种修辞,是人们为了表达自己的意愿或情感而使用的一种形式.
强调句的句构如下：
"It is (was)+ 被强调部分+ that (who) + 句子其他部分"
从强调句句构可以看出,强调句即便强调时间、地点也不能用when或where,而只能用"that"当然如果强调人时,用that/who都可以.
强调时间：It was yesterday evening that my father did the experiment in the lab.(注意没有用when)
强调地点：It was in the lab that my father did the experiment yesterday evening.(注意没有用where )
希望回答对提问者有所帮助.

用强调句型：“It is（was）＋被强调的部分＋that（who）＋原句其它部分”来强调说话人的意愿：
It was on Monday night that all this happened．所有这一切发生在周一晚上。
It's me who he blamed．他怪的是我。
这里强调任何成分都可以用that，强点人时也可以用who.
但不可以用when.
表示强调的句型还有：
强调句 强 调 句
强调句是一种修辞，是人们为了表达自己的意愿或情感而使用的一种形式,主要有如下几种形式:
1．用助动词“do（does／did）＋动词原形”来表示强调：
He does know the place well．他的确很熟悉这个地方。
Do write to me when you get there．你到那儿后务必给我来信。
2．用形容词 very，only，single，such, last 等修饰名词或形容词来加强语气：
That's the very textbook we used last term．这正是我们上学期用过的教材。
You are the only person here who can speak Chinese．你是这里唯一会讲汉语的人。
Not a single person has been in the shop this morning．今天上午这个商店里连一个人都没有。
How dare you buy such expensive jewels？你怎么敢买这么贵的宝石呢？
He is the last person I want to see in this world! 我最不想看他了!
3．用in the world，on earth，at all等介词短语可以表达更强的语气（常用于疑问句):
Where in the world could he be？他到底会在哪儿？
What on earth is it？它究竟是什么？
Do you know at all？你到底知不知道？
4．用感叹句来表示强烈的感情，突出说话人的情感：
How interesting a story it is！这是一个多么有趣的故事啊！
Oh，what a lie！啊，真是弥天大谎！
5. 用重复来表示强调：
Why！why！The cage is empty！啊！啊！箱子是空的。
They walked for miles and miles．他们走了好多英里。
6．用倒装句（也就是将要强调的句子或被强调的部分置于句首）来加强语气：
On the table were some flowers．桌上摆着一些花。（强调地点）
Many a time have I climbed that hill．我多次翻过那座山。
Only in this way，can we solve this problem．只有这样，我们才能解决这个问题。
7．用强调句型：“It is（was）＋被强调的部分＋that（who）＋原句其它部分”来强调说话人的意愿：
It was on Monday night that all this happened．所有这一切发生在周一晚上。
It's me who he blamed．他怪的是我。
8．用If来表示强调：
1）If从句＋I don't know who／what，etc．does／is／has，etc．；主语部分也可以用nobody does／is／has，etc．或everybody does／is／has，et c．来代替（这里的if从句往往是正话反说，反话正说）：
If he can't do it，I don't know who can．要是他做不了这件事，我不知道还有谁能做。（强调只有他能做）
If Jim is a coward，everybody is．要是吉姆是个胆小鬼，那么人人都是胆小鬼。（强调吉姆不是胆小鬼）
2）if从句＋it be主句（此用法可看成是第8中强调句型的变形，即把所要强调的内容放在it be的后面，把其它内容放在由if引导的从句中）：
If anyone knew the truth，it was Tom．如果说谁了解事实的真相，那便是汤姆。
If there is one thing he loves，it is money．如果说世界上还有他爱的东西，那便是金钱。
9．用破折号、黑体字也可以表示强调，加强语气：
It's because of hard work—ten years of hard work．那是因为艰苦的工作--十年艰苦的工作！
He began the work in late May．他在五月底开始的这项工作。（强调时间）
强调句的练习
1. ---Were all three people in the car injured in the accident?---No,___ only the two passengers who got hurt.
A. it was B. there is C. it were D. there was
2. ---Who is making so much noise in the garden? --- ___ the children.
A. It is B. They are C. That is D . There are
3. It was ___ she was about to go out ____ the telephone rang.
A. when ; that B. so; that C. before; then D. when; before
4. It was ___ he said ___ disappointed me.
A. what; that B. that; what C. that; when D. it; when
5.____ that silver is not widely used as a conductor?
A. Why is B. Is it why C. Why is it D. Why is that
6.---I can’t find Mr. Smith .Where did you meet him this morning?--- It was in the hotel ___ he stated.
A. that B which C. the one D. where
7.It was in the small house ___ was built with stones by his father ___ he spent his childhood.
A. which; that B, that ;where C, which; which D. that; which
8.It was ___ it was raining so hard that we had to stay at home all day.
A. since B .for C. as D. because
9.Is ____ three hours ____ the boy ___family is poor to come to school on foot?
A .it ;that; whose B. it; that it takes; whose C. it for ;that it takes; whose D. it; when ;that
10. his wife left him without saying goodbye.
A. that B .which C .when D. in which
11. It is a winter night ___he spent with me last night.
A. that B. where C. as D .when
12It is the young man ___ looked for ___ caught the murderer.
A. that; who B. that; they C. they ;that D they ;which
13.It was ____ my teacher worked ____ I work hard.
A. where; that B. where； where C .that; that D. that ;where
14.It was evening__we reached the little town of Winchester.
A that B. until C. since D. before
15.It was until dark ___ he found ___ he thought was the correct way to solve the problem.
A. that; what B. that; that C. when; what D. when; that
16.It was until last year that he ___.
A. left school for a new start
B .came to realize the importance of learning English.
C. worked as an English teacher at a middle school
D .set out to build a new house of his town.
17.It is the ability to do the job ____ matters ,not where you come from or what you are.
A. one B. that C .what D. it
18. I don’t know ____ that you stay here.
A. how long it is B. how long is it C. it is how long D. is it how long
19.It was _____ that caused him to serve dinner an hour later than usual.
A. we being late B. our being late C. we were too late D. because we were late
20.---what was the party like?---Wonderful. It’s years _____ I enjoyed myself much.
A. after B. before C .that D. since