The first sentence is at the first level, and the fifth level (dominant seventh chord) is at the first level. The chord connections in the second sentence are the same as in the first sentence. The third sentence is more complicated. One section can use subordinate seven, the second section can use main (level one) and three sections to proceed to subordinate (level 4), and the fourth section should use first level. The 1642 6 in the fourth sentence can use level 4 or level 2 minor seventh chords. The following section uses two chords, level 1 and level 5 seventh chords (or level 5 major triads), and finally enters the first level major chord. On three chords.