Complex sentence: Lim Jeong Hee debuted with Big Hit in 2005 and in 2007 became part of the mixed-gender trio 8Eight with Baek Chan and Lee Hyun.
Split into simpler sentences: Lim Jeong Hee debuted with Big Hit in 2005. In 2007, Joohee became part of the mixed-gender trio 8Eight with Baek Chan and Lee Hyun.