单选题 The speaker went on and on, ______ to his listeners' obvious boredom.
【正确答案】 D
【答案解析】(oblivious不在意的)。句意为：发言人一直在讲话，对听众们显而易见的厌倦情绪毫不在意。A．obligated负有责任的；B．obsessive着迷的；C．obvious明显的。