Puccini and Bizet

First part of aria where voice sings a single note and mournful melody is in the clarinet.

Next part of aria, voice and full orchestra together

From Madame Butterfly, Act I, Butterfly's entrance.
Melody in strings with single notes in soprano chorus
Then melody in both strings and soprano solo
Then joined by tenor singing single note descant

From Bizet Pearl Fishers. Friendship duet. First it's melody in flute with singers only countermelody. Countermelody not exactly monotonic but still a lot of repeated notes and clearly melodically subservient.

Then after a bridge, bigger statement this time with melody and countermelody in the two voices.