Which of the following explanations regarding the high number of Caesarean operations is NOT true

A．Some mothers have passed the best age for a natural delivery.

B．Some mothers have fertility problems.

C．Some mothers favor the operations of this type.

D．Some mothers have had surgical operations on their fallopian tubes.

患小鹅瘟死亡的小鹅其剖解特征是（）

A.肝出血

B.小肠出现香肠样栓子

C.肺出血

D.鼻腔出血

E.小肠粘膜出血