original: Oen Siew Yock took over as principal in 2005 when Ong was transferred to Nan Chiau High School.
simplifications: Oen Siew Yock took over as principal in 2005 when Ong was sent to Nan Chiau High School. Oen Siew Yock became principal in 2005 when Ong was sent to Nan Chiau High School Oen Siew Yock became principal in 2005 when Ong moved to Nan Chiau High School. Oen Siew Yock took over as principal in 2005. Ong was transferred to Nan Chiau High School. Oen Siew Yock took over as principal in 2005. This was when Ong was transferred to Nan Chiau High School. Oen Siew Yock became principal in 2005.  Ong was transferred to Nan Chiau High School. Oen Siew Yock took over as principal in 2005. Ong went to Nan Chiau High School. Oen Siew Yock was principal in 2005 when Ong was transferred to Nan Chiau High School. Oen Siew Yock became principal in 2005. Oen Siew Yock started being a principal in 2005 when Ong was transferred to Nan Chiau High School.