银汞合金充填术要制洞，主要因为
A．充填材料黏结力差B．充填材料有体积收缩C．充填材料强度不够D．便于去龋E．充填材料美观性不够
参考答案：A
通常煤气经离心鼓风机压缩后温升为（）℃
A.5-10℃
B.10-20℃
C.20-30℃
In each production lot for a certain toy, 25 percent of the toys are red and 75 percent of the toys are blue. Half the toys are size A and half are size B．If 10 out of a lot of 100 toys are red and size A, how many of the toys are blue and size B ？（）
A.15
B.25
C.30
D.35
E.40
