____ it comes to traffic rules, I often come across such cases _____ the local drivers obviously know

 them but won't follow them. [ ]

A. If; why

B. As; which

C. Once; as

D. When; where

某工程项目合同工期为20个月，施工单位提交的施工进度计划如图2-1所示(时间单位：月)，各项工作均匀速施工。

为有效控制工程施工质量，咨询工程师对各工作进行了初步风险分析，风险对项日产生的影响见表2-1。