单选题 The teacher"s lecture on American history was three hours long, and Mary felt very ______.
【正确答案】 B
【答案解析】[解析] upset：失望的，沮丧的；bored：乏味的，无聊的；disturbed：干扰的；neglected：忽视的，疏忽的。根据句意可知，选项B为正确答案。