工序能力根据正态分布的特点，一般都用﹝﹞来描述。
A.3个标准差
B.6个标准差
C.3倍的平均数
D.6倍的平均数
参考答案：B
(2013·江西，25)Only when he apologizes for his rudeness ________ to him again.
A．I will speak
B．will I speak
C．do I speak
D．I speak
焦油蒸馏（常压）生产煤沥青二段温度应控制在（）℃。
A.290
B.360
C.400
D.420
