中国大学MOOC: Paid search, or pay-per-click (PPC) advertising, typically refers to the “_________ result” on the top or side of a search engine results page (SERP).
主观题
中国大学MOOC: Paid search, or pay-per-click (PPC) advertising, typically refers to the “_________ result” on the top or side of a search engine results page (SERP).