在施工及维修中，FCS能降低系统工程成本表现在多个方面，下列哪一项不是（）
A.硬件数量与投资
B.组态软件
C.维护开销
D.安装费用
参考答案：B
已知a，b，c为△ABC的三边，且满足a2c2-b2c2=a4-b4，试判定△ABC的形状．
Mark _____ have hurried. After driving at top speed, he arrived half an hour early. [ ]
A. needn't
B. wouldn't
C. mustn't
D. couldn't
