Private Sub Timer1_Timer()
Timer1.Interval = 100
Timer1.Enabled = True
If linejs = 0 Then
   Call fx(90)     '画第一根线
   linejs = 1
ElseIf linejs = 1 Then
   Call fx(80) '画第二根线
   linejs = 2
ElseIf linejs = 2 Then
   Call fx(70)
   linejs = 3
ElseIf linejs = 3 Then
   Call fx(60)
   linejs = 4
ElseIf linejs = 4 Then
   Call fx(50)
   linejs = 5
ElseIf linejs = 5 Then
   Call fx(40)
   linejs = 6
ElseIf linejs = 6 Then
   Call fx(30)
   linejs = 7
ElseIf linejs = 7 Then
   Call fx(20)
   linejs = 8
ElseIf linejs = 8 Then
   Call fx(10)
End If
End Sub
Private Sub fx(ρ As Long)

Dim x2, y2 As Single

  
       For t = -20 To 65 Step 0.02
           Pq = Pk(t)
           x2 = 622 * Pq * (ρ / 100) / (101325 - Pq * ρ / 100)
           y2 = t + x2 / 2000 * (2500 + 1.84 * t) - x2
           If x2 <= 42 And y2 <= 65 Then
               Picture1.PSet (x2, y2), QBColor(4)
           Else
               Picture1.CurrentX = x2: Picture1.CurrentY = y2 + 1: Picture1.Print ρ; "%"
               Exit For
           End If
         
       Next t


End Sub
我现在这代码只能出现一根线，是为什么呢？

Pk?

也是我定义的一个函数

Private Function Pk(t) As Single
    Dim Ti As Single
    Dim c1, c2, c3, c4, c5, c6, c7 As Single                 
    Dim c8, c9, c10, c11, c12, c13 As Single
    c1 = -5674.5369: c2 = 6.3925247: c3 = -0.009677843
    c4 = 0.00000062215701: c5 = 2.0747825E-19: c6 = -9.484024E-13
    c7 = 4.1635019: c8 = -5800.2206: c9 = 1.3914993
    c10 = -0.04860239: c11 = 0.000041764768: c12 = -0.000000014452093
    c13 = 6.5459673
    Ti = 273.15 + t
    If t < 0 Then
       Ln = c1 / Ti + c2 + c3 * Ti + c4 * (Ti ^ 2) + c5 * (Ti ^ 3) + c6 * (Ti ^ 4) + c7 * Log(Ti)
       Pk = Exp(Ln)
    Else
       Ln = c8 / Ti + c9 + c10 * Ti + c11 * (Ti ^ 2) + c12 * (Ti ^ 3) + c13 * Log(Ti)
       Pk = Exp(Ln)
    End If
End Function