按照时间管理矩阵，优先级A的任务特征是（）。
参考答案：重要而且紧迫
什么叫釉质钙化不良?什么叫釉质发育不良?两者的区别是什么?
______ of danger on the road at night ,the girl had to go home with a friend _______ her.
A．Being warned; accompanied
B．Having warned; accompanying
C．Warning; accompanying
D．Having been warned; accompanying
