And then he attended the Department of Mathematics , Chinese University of Hong Kong and he gained his PhD at University of Sussex in 1993 .
During his secondary education , Cheung attended St Francis Xavier 's School Tsuen Wan .
Then Cheung attended the Department of Mathematics , Chinese University of Hong Kong and Cheung gained Cheung 's PhD at University of Sussex in 1993 .
During his secondary education , Cheung attended St Francis Xavier 's School Tsuen Wan .