第4题:[单选题]---Look. Your grandfather is playing tennis again.---I'm glad he is in good health. Even though he is ________, he still plays tennis now and then. A.in the eighties B.at his eightieth C.in his eighties D.at the eightieth 参考答案:C
第5题: [单项选择]最晚萌出的乳牙为() A. 上颌第一乳磨牙 B. 下颌第一乳磨牙 C. 上颌第二乳磨牙 D. 下颌第二乳磨牙 E. 上颌乳尖牙 参考答案:C