题目

单击窗体后，文本框Text1、Text2中显示的内容是( )Private Sub Form_Click( )Dim x as Integer, n as Integer x=1 n=0Do While x < 20 n=n+1 x=x * 3LoopText1.Text=Str(x)Text2.Text=Str(n)End Sub A . 27 3 B . 3 27 C . 20 3 D . 3 21 答案：AVmL Al2(SO4)3溶液中含aSO42-，若把此溶液取一半加水稀释至2V mL，则稀释后溶液中Al3+的物质的量浓度为（   ）                                A．mol/LB．mol/LC．mol/LD．mol/L