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举一反三
【单选题】电子射程的含义为（）。
A.
电子线中心轴上最大剂量点的深度Rioo
B.
电子线PDD剂量跌落最陡点的切线与Dm水平线交点的深度
C.
电子线入射表面下0.5cm
D.
有效治疗点深度R85
E.
固定深度2cm
【单选题】Ladies and gentlemen, welcome to Dalian, a famous summer resort ( 避暑胜地 ) and one of the best tourist cities in China. With clear sky, green mountains, blue seas, fine beaches, clean streets and lovely...
A.
comes in the best season.
B.
is here to join more tourists
C.
may not stand the heat here.
D.
is traveling back home.