桩冠修复时，一般要求根尖部保留充填材料长度为
A．0.5～1mmB．1～2mmC．2～3mmD．3～5mmE．5～8mm
参考答案：D
His money is ______ mine . [ ]
A. twice more than
B. more than twice
C. more twice than
D. two times more than
渗透剂的（）大小能影响渗透速率的快慢
