Complex sentence: Bartók researched folk melodies, and their influence is felt throughout the work; for example, the second main theme of the first movement, as played by the 1st oboe, resembles a folk melody, with its narrow range and almost haphazard rhythm.
Split into simpler sentences: Bartók researched folk melodies, and their influence is felt throughout the work. For example, the second main theme of the first movement, as played by the first oboe, resembles a folk melody, with its narrow range and almost haphazard rhythm.