unit1 SectionA 1b , unit2 SectionA 2a2b , unit3 SectionB 2a2b , unit4 SectionB 2a2b, unit5 SectionA 1b , unit6 SectionA 1b , unit7 SectionA 1b ,unit8 SectionA 1b , unit9 SectionA 1b , unit10 SectionA 2a2b