单选题 I must have hung ______ for ten minutes before the telephone operator put me through.

【正确答案】 C

【答案解析】(hang on不挂断)。句意为：接线员给我接通之前，我必须十分钟不挂断电话。A．hang up挂断电话；B．hang round闲荡；D．hang over遗留下来。