常見問題：
問：4. Q: What was Secret's debut song? 答： A: Secret's debut song was "I Want You Back," released in 2009.
問：6. Q: What is Secret's most popular song? 答： A: Secret's most popular song is "Poison," which was released in 2014 and became a huge hit in South Korea.
問：8. Q: Has Secret appeared on any variety shows? 答： A: Yes, Secret has appeared on various South Korean variety shows, such as "Invincible Youth," "Law of the Jungle," and "Hello Baby."