单选题 As there was a power cut in the hospital, the surgeon had to ______ the operation.

【正确答案】 C

【答案解析】call off意为“取消，停止”。A．call for意为“需求，需要”；B．call on意为“短暂地访问，拜访”；D．call up意为“使想起，使忆起”。