A:CuCl2 CH3COOH NaOH
B:HCl H2SO3 NaHCO3
C:HF HCl CH3COONa
D:NH4Cl HCl CH3COONa
找规律补充图形.
Jack is ______ 8-year-old boy. He often collects things for Project Hope.
— He has few friends to share his joy and sadness, _____ he?
— _________. It’s really bad for him to keep quiet all the time.