生产水泥时，需要加入适量的石膏以调节水泥的凝结速度，石膏的用量必须严格控制，否则过量的石膏会造成水泥的（）现象。
A. 凝结速度加快
B. 凝结速度减慢
C. 安定性不良
D. 强度降低
查看答案
水泥安定性试验时，调整好沸煮箱内的水位，沸煮试件应保证在30min±5min内加热水至沸腾，并恒沸（ ）。
A. 3ｈ±15min
B. 3ｈ±5min
C. 5ｈ±15min
D. 5ｈ±5min
关于雷氏法测定水泥安定性描述错误的是（ ）
A. 净浆装入雷氏夹后应在养护箱内养护24h±2h
B. 试件需要进行沸煮
C. 沸煮时恒沸时间为180min±5min
D. 沸煮时指针向下
Which topic is polite to talk about when you meet someone in business for the first time?
A. job responsibilities
B. age
C. love affairs
Which topic is polite to talk about when you meet someone in business for the first time?
A. weather
B. age
C. marriage
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