计算(2004﹣π)0的结果是[ ]
A.0
B.1
C.2004﹣π
D.π﹣2004
答案:B
His composition is excellent _____ some spelling mistakes. [ ]
A. except
B. except for
C. except that
D. besides
联锁操作是由()操作中心启动或停止的操作方法。
A、系统
B、岗位工
C、联锁