过期妊娠患者分娩过程中下列哪些因素增加：
A．头盆不称
B．肩难产
C．活跃期停滞
D．羊水栓塞
E．产后出血
参考答案：A,B,C,E
食管后方毗邻的结构不包括（）。
A.食管后间隙
B.奇静脉
C.右肋间后动脉
D.胸导管
E.心包
In an animal behavior experiment, 50 tagged white pigeons and 200 tagged gray pigeons were released from a laboratory. Within one week, 88 percent of the white pigeons and 80.5 percent of the gray pigeons had returned to the laboratory. What percent of the total number of pigeons returned to the laboratory ？（）
A. 80.5
B. 82
C. 82.5
D. 85
E. 86.5
