Music Theory
Inverted or complimentary intervals
Triad Identification - This one makes you think because you have to figure out if the key is major or minor depending on the quality of the chord. Answer the boxes from right to left. It will be easier than left to right.
Use these settings:
7th Chords: Dom., Maj, Min., Half, Full; All inversions; Show chord symbol
Triad Identification: Maj., Harm.; use inversions
MusicTheory.net - tutorials and exercises
Teoria.com - tutorials and exercises
Songs for Interval Recognition
Interactive Keyboard - Chord Structure