At what level is D7, or musical catechism, built?

Could you tell me at what level the dominant seventh chord is built? Beginning solfegists sometimes ask me this question. How can you not give me a hint? After all, for a musician this question is like something out of a catechism.

By the way, are you familiar with the word catechism? Catechism is an ancient Greek word, which in the modern sense means a summary of any teaching (for example, religious) in the form of questions and answers. This article also represents a range of questions and answers to them. We will figure out at what stage D2 is built, and at which D65.

At what stage is D7 built?

D7 is a dominant seventh chord, it is built on the fifth degree and consists of four sounds arranged in thirds. For example, in C major these sounds will be:

At what stage is D65 built?

D65 is a dominant fifth sixth chord, the first inversion of a D7 chord. It is built from the seventh stage. For example, in C major these sounds will be:

At what stage is D43 built?

D43 is a dominant tertz chord, the second inversion of D7. This chord is built on the second degree. For example, in the key of C major it is:

At what stage is D2 built?

D2 is the dominant second chord, the third inversion of D7. This chord is built from the fourth degree. In the key of C major, for example, D2 is arranged according to the sounds:

In general, it would be nice to have a cheat sheet, by looking at which you could immediately see where each chord is built. Here is a sign for you, copy it into your notebook and then you will always have it at hand.