Final answer:
Robert Frost shared the practice of writing in everyday language with his modernist peers, focusing on familiar objects and natural scenes, while still using traditional poetic structures.
Step-by-step explanation:
The practice that Robert Frost had in common with his modernist peers was writing in everyday language. Even though Frost is often associated with modernist poets, his work is notable for its clarity and accessibility, characteristics that made his poems popular among a wide audience. Unlike many of his contemporaries, who often used experimental techniques, wrote in free verse, and engaged with the complexities of inner consciousness, Frost's poetry focuses on familiar objects and everyday situations.