VB FOR问题

1.
Private Sub Command1_Click()
For i = 1 To 100
If i Mod 3 = 0 And i Mod 7 = 0 Then Text1.Text = Text1.Text & i & " "
Next i
End Sub

2.
Private Sub Command2_Click()
Dim flag As Boolean
For i = 3 To 100
flag = True
For j = 2 To i - 1
If i Mod j = 0 Then
flag = False
Exit For '如果flag为false，即i可以被除了1和它本身外的其他数整除，i不是素数，退出该循环
End If
Next j
If flag = True Then Text1.Text = Text1.Text & i & " " '当flag为ture时，即i除了1和其本身外，没有任何数可以被他整除,该数为素数
Next i
End Sub

Private Sub Command1_Click()
Text1.Text = ""
Dim i As Integer
For i = 7 To 100
If i Mod 3 = 0 And i Mod 7 = 0 Then
Text1.Text = Text1.Text & i & "/"
End If
Next
End Sub

Private Sub Command2_Click()
Text1.Text = ""
Dim i As Integer
Dim j As I