[问答题] 简述压扁层理和透镜状层理的基本特征。

商标 某初产妇，27岁，停经31周，因阴道流血1天收入院。患者于1日前无明显诱因出现阴道流血，量较多，无腹痛。入院检查：血压120/70mmHg，尿蛋白（-），下肢水肿（-），血色素82g/L。B超提示胎盘位于子宫右后壁延至前壁覆盖官颈内口。该孕妇目前收入院观察。 列出主要的护理措施。 对立原理 每损伤达到1mm厚度绝缘层，应包缠（）自粘带。 ["一层","两层","三层","四层"] Which three objectives would be met by designing Layer 3 switching in the Campus Backbone of a medium size installation?（） [" scale to a large size"," increase router peering"," provide a flexible topology with no spanning tree loops"," control broadcasts in the backbone"] 简述压扁层理和透镜状层理的基本特征。