在进行临边作业时设置的防护栏杆高度应为(),并加挂安全立网。
A、1.5m
B、1.0m
C、2.5m
D、2.0m
参考答案:A
以下引起痛风的物质代谢障碍是()
A.水盐
B.蛋白质
C.氨基酸
D.嘌呤
E.核糖
I want to know how much _____ about the table manners around the world. [ ]
A. do they know
B. they know
C. did they know
D. have they knows