She returned to school and earned good grades to graduate.
An abstract noun is a noun that you can't feel, hear, taste, smell, and see. Like hope. A concrete noun is a noun that you CAN feel, hear, taste, smell, and see.
So the abstract noun in this sentence is not choir, but harmony.
hope it helps!
1. "Get thee back into the tempest and the Night's Plutonian shore!" (Plutonian alludes to the Roman god of the underworld)
2. "On the pallid bust of Pallas just above my chamber door." (Pallas alludes to a Greek titan god)
