Here are 2 sentences for illustration:
1)Do you know what is the matter?
2)Do you know what the matter is?
Which arrangement is correct? and why it is correct?
And how about the below sentences:
Do you know what is it/door catch/...?(any other noun or pronoun can be put here)
Do you know what it/door catch/...is?
Looking forward to your clarification.
countless thanks for you.
"Do you know" introduces an indirect question and the rest of the question (i.e. after "Do you know") is usually an affirmative construction:
Do you know what time it is?
Do you know why he said that?
Do you know how long they have been married?
Thank you, Harry.
Thank you, Philly.
So kind you are.
Thank you cordially.