This leaves fertile soil unprotected and prone to erosion.这会让肥沃的土壤暴露在外，使其容易受到侵蚀。You are playing Russian roulette every time you have unprotected sex.行房时不采取避孕措施是非常危险的。Machinery was often unprotected and accidents were fre...
主要包括信号交叉口放行方法设计 、 渠化设计和信号优化设计.The primary step includes discharging mode design , signal design and channelization design of signalized intersection.水运建设迈出新步伐, 正式启动嘉陵江全江渠化项目.Waterborne construction strides new step, star...