以下哪一项不是梅毒的感染途径（）
A.性接触
B.血液传播
C.垂直传播
D.接吻
E.蚊虫叮咬
参考答案：E
羊膜细胞来源于外胚层。
一Is there a computer on Miss Li's desk?
—_____. There are only some books on it. [ ]
A. Yes, there is
B. No, there isn't
C. Yes, it is
D. No, it isn't
