when did we use 'auxiliary verb' in wh-questions?

[jesicaporter]

Hello Teachers,
can somebody help me about the below sentence?
20,000 people came to India when they got married.
Now i am going to ask about counts of people who came to india when they got married

"How many people came to India when they got married?"

but why we don't use: "How many people did come to India when they got married?"

another example:
sarah saw jack .
who saw jack?
but,why don't use:" who did see jack?"

when use 'auxiliary verb' - do/doses/did- in wh-questions?

i am so confused about that.

sorry for my english, it is not my native language.
thanks so much for your help.

 

[5jj]

When the question word is the subject of the verb, we do not need auxiliary DO:

Sarah saw Jack.
Who saw Jack?
Who did Sara See?

The cow ate the grass
What ate the grass?
What did he cow eat?

Ten people came.
How many people came?

I saw ten people.
How many people did you see?

 

[jesicaporter]

thanks alot for your quick and great reply,
but why ? is there any resons for that?

and another questions?
in the sentense sarah saw jack , who did sarah see? jack
when did we using auxiliary verb using who ?

and according to your example in the below sentense:
The cow ate the grass
1-What ate the grass?
or
2-who ate the grass?
which one correct ? 1 or 2
you said what ate the grass?

 

[5jj]

[STRIKE]t[/STRIKE]Thanks alot for your quick reply,
but whyno space?. [STRIKE]i[/STRIKE]Is there any reason[STRIKE]s[/STRIKE] for that?
[STRIKE]and[/STRIKE] I have another question[STRIKE]s?[/STRIKE].
[STRIKE]i[/STRIKE]In the senten[STRIKE][STRIKE]s[/STRIKE][/STRIKE]ce "[STRIKE]s[/STRIKE]Sarah saw [STRIKE]j[/STRIKE]Jack no space,who did [STRIKE]s[/STRIKE]Sarah see?

Please use a capital letter for the the at the beginning of a sentence, and for names of people. Do not leave a space before a punctuation mark.

 

[Tdol]

but why ? is there any resons for that?

Because it's the subject- language patterns don't require more reason than that, I'm afraid.