A:﹣2n(2n﹣1)
B:﹣3n(n+3)
C:﹣4n(2n+1)
D:﹣6n(n+1)
The factory ______ its waste into the river, but now it deals with the waste in a new way.
如图,将△ABC的三边分别扩大一倍得到△A1B1C1(顶点均在格点上),若它们是以P点为位似中心的位似图形,则P点的坐标是( ).
如图所示,弹簧测力计下挂着铁块P,其正下方的水平地面上放着一块条形磁铁Q,P和Q均处于静止状态.已知P和Q的重力分别为G和3G,若弹簧测力计的示数为2G,则下列说法正确的是