1. Why is the story entitled the Soul of the Great Bell?

The metals aren't compatible with each other. When Ko-ngai sacrificed herself as the astrologer said,the bell rang/sounded perfectly. It was pleasant to the ear. It was called the 'Soul of The Great Bell' because of the sacrifice the daughter did.

i'm thinking it would be when compound subjects are joined by or, nor,either-or, neither-nor.

remember, the goal of an adjective clause is to add more information to a noun or a pronoun. as you can see from the examples above, you can add information by including a longer adjective clause or tighten up a sentence by turning the adjective clause into an adjective phrase.