弹簧压力表的检定应在环境温度（）条件下进行。
A.15°С±5°С
B.20°С±5°С
C.22°С±5°С
D.25°С±5°С
参考答案：B
— do you think of talk shows?
— I love them.[ ]
A. Why
B. How
C. What
D. When
牙拔除后至少多长时间，拔牙创内形成凝血块而将创口封闭（）
A.5min
B.10min
C.15min
D.30min
E.45min
