对应于一个程序中所有检测元件状态开关量所构成的二进制数码称为该程序的（）。
A、特征码
B、BCD码
C、编号
D、动作顺序
参考答案：A
如果点P（m-1，2-m）在第四象限，则m的取值范围是______．
_ Who's that boy reading in the garden? Is it David?
_ It __________ be David. I saw him in the classroom just now.[ ]
A. must
B. can't
C. may
D. shouldn't
