What's the grammatical structure of 这是你第一次来中国吗？ I am confused about the sentence 这是你第一次来中国吗？
I think I know the correct translation: "Is this the first time you go to China?"
However, I am confused about the grammatical structure of the sentence.

I would expect that when the structure 这是 (something) 吗？is present, then (something) is a noun phrase. For example:


这是你要的吗？(Is this what you want?)
这是你点的菜吗？(Is this the dish you ordered?)


你要的 (what you want) and 你点的菜 (the dish you ordered) are noun phrases (right?). However, I can't identify 你第一次来中国 as a noun phrase. 

If 你第一次来中国 is a noun phrase: What is the structure that makes it a noun phrase? Why does it not say 你的第一次来中国? Isn't 次 a measure word? Why can it be followed by a verb?

If 你第一次来中国 is not a noun phrase, how can it be used with 这是 (something) 吗？?
Simply put. There is always S V O structure in Chinese. 

In this case, 这(this) is the S, 是(is) is the V, 你第一次来中国 (your first time coming to China) is the object phrase.

PS 你第一次来中国 = 你的第一次来中国. (The 的 in the first sentence got dropped)