单项预试验
参考答案：
根据工作的需要，有目的地检查某一类成分或者某一成分。
He was late for school, because he_____ the school bus. [ ]
A. failed
B. missed
C. lost
D. missing
设x=4,y=6，则以下不能在窗体上显示出"a=10"的语句是______。
A．Print A=x+y
B．Print "A=";x+y
C．Print "A="+str(x+y)
D．Print "A="&x+y
