Answer:
I and U
Explanation: That took a lot longer than I thought
In tonal Western classical music (music with a tonic key or "home key"), the most frequently encountered chords are triads, so called because they consist of three distinct notes: the root note, and intervals of a third and a fifth above the root note. ... A series of chords is called a chord progression
As an adhesive for two materials that aren't too smooth.
