1．写出下列命题的否定．(1)∀x∈R,2x2＋3x＋4＝0；________________________________________________________________________；(2)所有的等边三角形都全等；________________________________________________________________________；(3)锐角都相等；_________________________...

时间:2024-11-17 17:25栏目:幼儿/小学教育