第6题: [单项选择]According to the old-timers, on two occasions ______. A. the water of the lake turned red B. lake water sprouted into the air C. the Gnats invaded the countryside D. fish in the lake suddenly died 参考答案:D 答案解析:原文：In 1833 and again in 1846，fish in the lake suddenly died．
第13题: [单项选择]女性，32岁。服用复方炔诺酮避孕，停药7天仍无月经来潮，应 A. 立即停药改用其他避孕方法 B. 于5天后开始服第2周期药物 C. 加用黄体酮 D. 立即停药检查原因 E. 于当晚开始服第2周期药物 参考答案:E 答案解析:停药7天未来月经，于当晚开始服第2周期药物；再次无月经出现，宜停药明确原因。
