* * 内表面被覆的上皮是（）
A.单层柱状上皮
B.单层扁平上皮
C.单层立方上皮
D.复层扁平上皮
E.假复层纤毛柱状上皮
参考答案：D
The book was written in 1946, __________ the education system has witnessed great charges.
A．when
B．during which
C．since then
D．since when
含二硫化二砷矿物药是
A．轻粉
B．红粉
C．白降丹
D．雄黄
E．朱砂
