简述广告事前测试的两种基本方法。
用变质程度浅的炼焦煤炼焦，得到的焦炭有下列：（）特点。 ["裂纹多","不抗碎","焦炭块度小","不耐磨"]
（）决定一个国家、一个民族的方向和前途，是国家和民族的生命线。 ["奋斗","竞争","战略","优势"]
Refer to the router topology shown in the graphic. Assuming that all routers are running OSPF, which statements correctly describe how the routers exchange routing information?（） [" Denmark exchanges with Utah, Paris, and Berlin."," Utah exchanges only with Denmark."," Berlin exchanges with Denmark, Utah, and Paris."," Paris exchanges only with Denmark."," Denmark exchanges with only Paris and Utah."]
牛顿经典力学创立，当初有科学家认为所有涉及到的物理学问题都可以归结为不变的引力和斥力，因而只要把自然现象转化为力就行了。结果到后来，“力”成了对现象和规律缺乏认识的避难所，把当时无法解释的各种现象都冠以各种不同力的名称．这一事实表明经典力学的创立（）。 ["对自然科学的影响有得也有失","标志着近代自然科学的诞生","促进了社会文明的发展","使人类在思想上获得了彻底解放"]
多型现象
