单项选择题
A．prostatic portion of urethra B．membranous part of urethra C．where it crosses superior aperture of lesser pelvis D．where it pierces into the unrinary bladder E．internal urethral orifice
A．deiaphragm B．superior portion of duodenum C．head of pancreas D．suprarenal gland E．pylorus
A．hepatic vein B．cyctic duct C．common bile duct D．left gastric vein E．celiac trunk