请求语法指点 I did write down the number on the paper.

请求语法指点 I did write down the number on the paper.
这是新东方听力上的一句话 为什么要用DID 这里不用的啊 用了就两个动词了 这又不是否定和疑问 不需要组动词的.

这是英语中的强调,用do、 does、did,此句可翻译为：我确实曾……
英语中的强调:
在英语中可以用多种方法表示强调,现在小结如下：
1． 强调句型 It is /was …that /who…
I met John in the street yesterday afternoon.
It was I who/that met John in the street yesterday afternoon.
It was John who/that I met in the street yesterday afternoon
It was in the street that I met John yesterday afternoon.
It was yesterday afternoon that I met John in the street.
此句型可以强调主语,表语,宾语,状语等,强调人时可以用who或that其他则用that .此句型中也可以用情态动词.
2.用助动词do .does did.只用于陈述句（肯定句）,祈使句,去掉后句意不变,不影响句意表达.
Do come to school early.
I do believe it .
3.倒装句,避免头重脚轻,把强调部分提前.
From the speaker on the wall comes from a doctor’ s voice ,“Good
morning!”
On one side of Tian an men Square stands the Great Hall of the
People
On River Thames lies a beautiful city where the musician was born.
4.反身代词,在句中做成分时不是加强语气,可以去掉时是加强语气,表示强调.
He himself said so.
You may go and ask the teacher about that yourself.
5.only,just,much,still,alone,terribly,simply,very,any,at
all,enough,even等用于 句子中表强调
Even a child can understand it.
He has just gone to Beijing.
That’s good enough,I shall say.
但only位置不同,强调成分不同.
Only I solved the problem.
I only solved the problem.
I solved only the problem.
6.---ever.用于关系代词,关系副词,疑问代词,疑问副词之后,表强调.
I don’t care whoever it is.
You can choose whatever you want.
Wherever you go ,whatever you do ,I’ll be here waiting for you.
7.在口语中,用for ages/years,die,on earth,in the world等表强调.
I am dying for knowledge.
What on earth are you doing here?
8.在口语中,用重读方式表强调,强调哪,重读哪.
9.在书面语中,用大写,斜体,黑体或其他标点符号等.
10.用进行时态表强调.
He is always helping others.
You are looking terribly ill today.
11.用重复手段.
His home is far,far away from here.
Long,long ago,there lived a prince.
12.同义词连用.
To join the Party is her highest aim and object.
13.双重否定.
It is never too late to learn.
No one does not know Li Bai.
14.not only… but also… ,as well as
He is a writer as well as a singer.
15.用most.
I shall most certainly go there.
This is a most useful book.
She is a most beautiful girl.