编程实现：产生n道十进位的算术运算，界面自定

Private Sub Command1_Click()
Const n = 20
Dim i As Long, j As Long
Dim a As Double, b As Double, c As Integer, d As Integer, e As Integer

For i = 1 To n
Randomize
c = Int(Rnd * 4 + 1)
Randomize
d = Int(Rnd * 6 + 1)
Randomize
e = Int(Rnd * 6 + 1)
Randomize
a = Rnd * 10 ^ d
Randomize
b = Rnd * 10 ^ e
Select Case c
Case 1
Print CStr(a) & Chr(9) & "+" & Chr(9) & CStr(b) & Chr(9) & "=" & Chr(9) & CStr(a + b)
Case 2
Print CStr(a) & Chr(9) & "-" & Chr(9) & CStr(b) & Chr(9) & "=" & Chr(9) & CStr(a - b)
Case 3
Print CStr(a) & Chr(9) & "*" & Chr(9) & CStr(b) & Chr(9) & "=" & Chr(9) & CStr(a * b)
Case 4
If b = 0 Then b = 1