Seventh chords are the most common extension of the basic 3-note triad you come across.
A seventh chord is built by adding an extra note to a triad which is an interval of a 7th above the root note.
e.g. If you build a triad on C you will use the notes (C-E-G). If you add a another note a 7th above C then you will have C-E-G-B. You have just created a basic seventh chord.
THE 5 TYPES OF SEVENTH CHORDS
There are 5 types of 7th chord you will come across and want to use in your music. Each one gives a characteristic sound which will help you when composing music.
It all with lines and it has black marks whay is this V
Musical instruments of different types playing the same note may often be identified by the timbre of their sounds. Timbre is tone color, or tone quality which distinguishes different types of sound production.
The answer would be Ritornello form.
It is D I think. Hope I helped
