第3题: [单项选择]乳牙滞留是指() A. 继承恒牙已萌出,按时脱落的乳牙 B. 乳牙牙根大部分吸收,未能脱落的乳牙 C. 乳牙牙根吸收2/3,未能脱落的乳牙 D. 恒牙未萌出,保留在恒牙列的乳牙 E. 继承恒牙缺失,未能脱落的乳牙 参考答案:D 答案解析:乳牙滞留包括两种情况,继承恒牙已萌出、未按时脱落的乳牙和恒牙未萌出、保留在恒牙列的乳牙。故A、B、C、E错。
第19题: [单项选择]Questions 11 to 18 are based on the conversation you have just heard. A. Because she has to work. B. Because she doesn’t want to. C. Because she is going out for dinner at a restaurant. D. Because she is meeting someone in a restaurant. 参考答案:A 答案解析:[听力原文] M: The Students’ Club is having a party this evening. Can you come and help with the drink