秦始皇“焚书坑儒”的历史背景和原因是（）。 ["秦朝完成大一统的格局","废分封，行郡县","百家争鸣的局面阻碍了秦朝对六国在思想上的统一","当时一些方士、儒生借古代圣贤的言论批评时政"]
"Cast iron has poor corrosion resistance to sea water, especially in the presence of bronzes" Implies（）. ["east iron is a cheap material","cast iron can pollute sea water","cast iron has mere corrosive than bronzes to sea water","cast iron is more corrosive to sea water when it meets with bronze"]
由于RGB颜色模式的三原色在合成时可以产生白色，因此，称此颜色模式为（）。 ["加色模式","减色模式","互补色模式","印刷色模式"]
下列哪些特种设备的设计文件，应当经国务院特种设备安全监督管理部门核准的检验检测机构鉴定，方可用于制造（） ["锅炉","压力管道","客运索道","大型游乐设施"]
管路安装标准化操作前检查的内容有（） ["检查工具齐全","刹车灵活好用","流程正确","配电箱不带电","不渗不漏"]
简述植物病害的病状类型。
