轧件所受的轧制压力增加，轧辊的弹跳值（）。
A.不变
B.减小
C.不确定
D.增大
参考答案：D
With the help of the German experts, the factory produced _____ cars in 1993 as the year before. [ ]
A. as twice many
B. as many as twice
C. as twice as many
D. twice as many
下列试剂中，哪些是常用的生物碱沉淀试液（）
A.碘化铋钾
B.碘化汞钾
C.磷目酸
D.硅钨酸
E.α-奈酚
