（）指出下列哪一个标准不是2000版标准中的核心标准.
A、ISO9001
B、GB/T19001
C、ISO10021
D、ISO9000
参考答案：C
— Why did you step on my foot?
— I am terribly sorry. I ____ it. [ ]
A. am not noticing
B. didn't notice
C. don't notice
D. haven't noticed
