由偶然性原因引起的质量特性值的变化在质量标准允许范围内波动称之为（）。
A.正常波动
B.异常波动
C.偶然波动
D.定期波动
参考答案：A
一个练习本0.8元钱，小东拿2元钱买两个练习本，还剩______元钱．
— I left my handbag on the train, but luckily someone gave it to a railway official.
— How unbelievable to get it back! I mean, someone _____ it. [ ]
A. will have stolen
B. might have stolen
C. should have stolen
D. must have stolen
