填空题Old Henry is over eighty but he is still in good（）（healthy）.
填空题I don’t think after-school（）（activity）will take too much time.
填空题All of us spent an（）（enjoy）day on the farm last Sunday.
问答题鸟类的主要特征是什么？
单项选择题哺乳动物区别于其它动物最显著的特征是（）
