为什么在强调句中，be只有is和was两种形式？

Question

如题所述

Answer 1

强调句型：It is/ was + 被强调部分（通常是主语、宾语或状语）+ that/ who（当强调主语且主语指人）+ 其他部分。
构成强调句的it本身没有词义，但它(it)是本句型的主语，所以其后面的be形式只有is和was两种形式。

Answer 2

对于it is (was)+被强调成分+that (who)... 的强调句来说 因为是it做主语 所以通常只有 一般时 it is 和过去时 it was 两种形式 非要举例写将来时 可以是 It will be your parents who clean after you.

请采纳

Answer 3

在强调句中，be动词的时态和后面的句子的时态应该一致，或皆用现在时，或皆用过去时，或皆用将来时，所以be动词不只两种形式，也可以用将来时will be的形式。
英语常用的强调结构是：It is (was) + 被强调部分(主语、宾语或状语)+ who (that)‥‥。一般来说，被强调部分指人时用who，指物时用that(但that亦可指人)。如原句为：
Richard wore his best suit to the dance last night. 理查德昨晚穿着他最好的一套衣服去参加舞会。
我们即可用强调结构来强调句中的主语、宾语和状语：
It was Richard who (that) wore his best suit to the dance last night. 是理查德昨晚穿着他最好的一套衣服去参加舞会。(强调主语)
It was his best suit (that) Richard wore to the dance last night. 理查德昨晚是穿着他最好的一套衣服去参加舞会的。(强调宾语)
It was last night (that) Richard wore his best suit to the dance. 理查德是昨晚穿着他最好的一套衣服去参加舞会的。(强调状语last night)
It was to the dance that Richard wore his best suit last night. 理查德昨晚穿着他最好的一套衣服是去参加舞会的。(强调状语to the dance)
强调结构强调状语时只可用that从句。
强调结构亦可强调某些状语从句，如：
It was because I wanted to buy a dictionary that I went to town yesterday. 我昨晚是由于想买一本字典而进城的。(强调because从句)
It is only when you nearly lose someone that you because fully conscious of how much you value them. 只有当你差点失掉一个人时，你才会充分意识到你是多么珍视他。(强调only when引导的从句)
在强调结构的who从句中，who也常用作宾语。如：
It must be your mother who you are thinking of. 你在想的一定是你的母亲。(who常代之以that，在正式文体中亦可用whom，强调宾语)
表语、宾语补语、定语偶尔亦可为被强调部分。如：
It was a doctor that he eventually became. 他最后成为的是一名医生。(表语一般不可用作被强调部分)
It’s dark green that we’ve painted the kitchen. 我们把厨房漆成的颜色是深绿色。
It was Richard whose mother I met. 我遇见的是理查德的母亲。
强调结构中的时态一般应一致，即主句与从句的时态应皆用现在时，或皆用过去时，或皆用将来时。如：
It is not I who am angry. 发怒的不是我。(皆用现在时)
It was my two sisters who knew her best. 是我的两个姐妹最了解她。(皆用过去时)
It will not be you who will have to take the blame for this. 对此须受责难的将不是你。(皆用将来时)
但有时主句与从句所用的时态并不一致。如：
It is Miss Williams that enjoyed reading novels as a pastime. 是威廉斯小姐以读小说来消遣。
It is these very novels that Miss Williams enjoyed reading as a pastime. 威廉斯小姐作为消遣所读的就是这些小说。
强调结构中的that与who在非正式文体中可以省略。如：
It was the President himself spoke to me. 是总统亲自和我谈了话。(省去从句的主语who)
It was the dog I gave the water to. 我是给那条狗水的。(省去从句的宾语that)
It was yesterday I first noticed it. 我是昨天开始注意到的。(省去连词that)
有时还可以省去句首的it is，如：
A good, honest trade you’re learning, Sir Peter! 彼得爵士，你学的是一种很好而诚实的一行啊!
强调结构中的被强调部分有时可入在句首，如：
Now was it that his life was done, and the fate which he could not escape was upon him. 就在这时，他的生命完结了，他所逃不脱的命运降临了。
希望我能帮助你解疑释惑。