____ to hospital in time, the wounded soldiers were saved at last.

A．Taken

B．Taking

C．Having taken

D．Being taken

投照根尖片时牙椅椅坐呈水平位，背靠呈垂直位，调节牙椅高度，使患者口角与医师腋部相平，患者坐位呈直立姿势，头部靠在头枕上，矢状面与地面垂直。投照上颌后牙时，________与地面平行。投照上颌前牙时，头稍低，使________与地面垂直。投照下颌后牙时，________与地面平行。投照下颌前牙时，头稍后仰，使________与地面垂直。