答案：A
B、若α⊥β，α⊥r，则β∥γ
C、若α⊥β，α∩β=a，b⊥a，则b⊥α
Jim is eight-year-old boy. He spends half _____hour playing _____ piano every day.
A．a; an; a
B．an; the; an
C．an; an; the
D．the; a; /
