题目

 With drink and food ____, the prisoner had to walk out of the cave where he was hiding. A. run out    B. run out of    C. running out    D. running out of 答案：B某些含氟（F）牙膏中含有一种化学式为Na2FPO3的物质．已知其中的氟元素化合价为-1价，则其中的磷元素的化合价为（ ）A．-5B．+1C．+3D．+5