简述物流信息系统的基本结构和主要功能。
《铁路技术管理规程》（普速铁路部分）在双线区间，仅限于整理列车运行时，方可使列车反方向运行，但旅客列车仅在正方向区间的线路封锁施工、发生自然灾害或因事故中断行车等特殊情况下，经铁路局调度所值班主任准许，方可反方向运行。
属于火花塞组成部分的是（）。 导电片。 接触头。 锡箔带。 调节板。
A medium-sized company has a Class C IP address. It has two Cisco routers and one non-Cisco router. All three routers are using RIP version 1. The company network is using the block of 198.133.219.0/24. The company has decided it would be a good idea to split the network into three smaller subnets and create the option of conserving addresses with VLSM. What is the best course of action if the company wants to have 40 hosts in each of the three subnets?（） Convert all the routers to EIGRP and use 198.133.219.32/27, 198.133.219.64/27, and 198.133.219.92/27 as the new subnetworks.。 Maintain the use of RIP version 1 and use 198.133.219.32/27, 198.133.219.64/27, and 133.219.92/27 as the new subnetworks.。 Convert all the routers to EIGRP and use 198.133.219.64/26, 198.133.219.128/26, and 133.219.192/26 as the new subnetworks.。 Convert all the routers to RIP version 2 and use 198.133.219.64/26, 198.133.219.128/26, and 133.219.192/26 as the new subnetworks.。 Convert all the routers to OSPF and use 198.133.219.16/28, 198.133.219.32/28, and 198.133.219.48/28 as the new subnetworks.。 Convert all the routers to static routes and use 198.133.219.16/28, 198.133.219.32/28, and。
《建筑施工安全检查标准》JGJ59-2011规定，基坑工程安全防护，当开挖深度超过（）及以上的基坑周边必须安装防护栏杆，防护栏杆的安装应符合规范要求。 0.8m。 1.2m。 1.8m。 2m。
道路运输过程中，经常导致事故的危险源主要集中在（）上。
