当两条直线相交成直角时，这两条直线互相平行．______．
由分析知：两条直线相交成直角时，那么这两条直线互相垂直；
故答案为：错误．
— How do the shops make money if they sell at such low prices?
— Manufacturers, it seems, are willing to bring down prices ____ big volume purchases. [ ]
A. under the name of
B. on behalf of
C. in return for
D. in preparation for
在草图设计时，颜色变化是很重要的实时诊断信息：绿色表示（）
A.受保护的约束
B.约束干涉
C.全约束
D.过约束
