肛管的长度是:() ["2cm","3cm","4cm","5cm","6cm"]
绘图题:画出两路进线、四路出线的双母线加旁路母线的接线方式。
在正常状态下,粪便储存在:() ["横结肠","降结肠","乙状结肠","直肠","以上均可"]
什么是种子寿命?
肛管直肠环的组成是:() ["外括约肌皮下部、浅部、深部、提肛肌","内括约肌下缘、外括约肌浅部、深部、提肛肌","外括约肌、耻骨直肠肌、髂骨尾骨肌","内括约肌下缘、外括约肌浅部、深部,耻骨直肠肌","内括约肌下缘、外括约肌皮下部、浅部、深部"]
简述种子发芽的条件。