当采用扣件式钢管做支撑模板的立柱时，每根立柱底部应设置底座及垫板，垫板厚度不得小于（）mm。
A.30
B.50
C.60
D.100
参考答案：B
Don't sit on the chair. There ________ on it.[ ]
A. is some water
B. are some water
C. is any water
D. are any water
标准体积管经检定后，检定证书应指明哪些内容？
