按照配送功能进行分类，配送成本大体可分为物品流通费、信息流通费和（）三大类。 ["人工费","维护费","保管费","配送管理"]
基本共射放大电路出现饱和失真时，其三极管输出特性的交流负载线上的静态工作点 一般是（）。 ["偏低","偏高","居中","都有可能"]
硝酸甘油扩血管作用机制（） ["阻断α1受体","激动β受体","阻断M受体","激动多巴胺受体","作为NO的供体"]
软件开发模型有几种？各自适合于什么场合？
On a Series 1010 lightweight access point， the alarm LED is flashing red， and all other LEDs are off. What is the lightweight access point indicating？（） ["It has lost contact with controller.","Its IP address already exists.","It requires a code upgrade.","It is operating normally."]
由（）衍生而成的化合物均为萜类化合物，此类化合物结构种类虽然非常复杂，但其基本碳架多具有（）结构特征。
