1.after two-year practice,he does well in typing(改为同义词)
after two-year practice,he becomes an _expert__ __in_ typing
2.robert still stays in Japan(改为否定句)
Robert ___doesn't__ stay in Japan
3.my mother usually helped me with my homework during the primary time (改为同意句)
4.my mother _used__ _to__ _help___ me with my homework during the primary time