Patients should not function on crownsjust after cementation ofthe crowns with a chemically-activated resin cement because()
A. the tooth will be sensitive
B. the bond needs time to mature
C. the crown may fracture
D. the cement shade will change drastically
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冷轧板的锈蚀跟()无关。
A. 下雨天气潮湿
B. 乳化液中Cl-含量高
C. 欠酸洗
D. 平整液吹扫不净
热轧板的纵裂会造成冷镀锌()缺陷。
A. 麻点
B. 条状锌起伏
C. 划伤
D. 边皱
已知当班生产出一级品1930吨,废品2吨,二级品20吨,三级品11吨,所用原料为2000吨,求当班成材率、合格率及一级品率?(三级品是不合格品)