Phrasal verbs are more than just a verb plus a preposition; they are idiomatic expressions where the combined meaning is often completely different from the original words. "Please extinguish your cigarette." Natural: "Please put out your cigarette."
Native speakers use phrasal verbs in about 80% of spoken communication. If you rely solely on "Latinate" verbs (like investigate instead of look into ), you might sound like a textbook rather than a person. Why Seek a "5000 Phrasal Verbs" List? 5000 phrasal verbs pdf
Clean up, drink up, cheer up.