单击命令按,下列程序的执行结果为 Private Sub Command1_Click() Dim a As Integer, b As Integer, c As Integer a=2: b=3: c=4 Print P2(c, b, A. End Sub Private Function P1(x As Integer, y As Integer, z As Integer) P1=2 * x + y + 3 * z End Function Private Function P2(x As Integer, y As Integer, z As Integer) P2=P1(z, x, y) + x End Function ( )。 A.21