1.What does a purple line in an irrigation system indicate?
1.灌溉系统中的紫线表示什么？
2.What is the minimum height for construction safety cones?
2.施工安全锥的最小高度是多少？
3.What is the minimum thickness for a 60-minute fire-rated wood door?
3.耐火 60 分钟的木质门的最小厚度是多少？
4.At what minimum height must workers wear approved fall restraints?
4.工人在多高的作业面必须佩戴经认证的防坠落装备？
5.What precaution is necessary when spraying toxic substances?
5.喷洒有毒物质时，需要采取哪些预防措施？
6.What is the correct distance ratio for ladder placement (base to wall vs. height to top support)?
6.梯子放置的正确距离比例（底部到墙面的距离与顶部支撑高度的比例）是多少？
7.What is a fire damper?
7.什么是防火阀？
8.What is the minimum size for roadway construction signs?
8.道路施工标志的最小尺寸是多少？
9.When is double-glazing required for windows?
9.什么情况下窗户需要安装双层玻璃？
10.What type of ladder is safest near electrical equipment?
10.在电气设备附近使用哪种梯子最安全？
