牙本质龋损在光镜下可看到微生物渗透至牙本质小管的区域是（）
A.坏死区
B.感染层
C.牙本质脱矿区
D.硬化区
E.修复性牙本质层
参考答案：B
Experience of this kind in both the U.S. and Europe well before the Second World War.
A．have conducted
B．have been conducted
C．had conducted
D．had been conducted
虚证闭经的治疗原则是：（）
A.补而通之
B.补益肝肾
C.健脾益气
D.养血活血
E.调补脾肾
