直肠手术可以采取骶尾入路的解剖根据是:() ["直肠壶腹前壁向前膨出","直肠后壁无腹膜遮盖","直肠后壁无直肠瓣","此处组织疏松","以上均不对"]
临床上用来定位内外括约肌分界的是:() ["肛门白线","齿线","牙线","栉膜","以上均不对"]
门静脉高压者出现痔出血,不宜做何种治疗:() ["口服中药","中药外洗","痔疮锭塞肛","手术结扎","以上均不对"]
齿线上的痔内静脉丛分布在何处最为显著:() ["左前、右后、左侧","右前、左前、左侧","右侧、右后、左前","右前、右后、左侧","左前、左后、右侧"]
简述我国将森林划分为哪几大林种。
我们通常所说的四旁林是指什么?