关于exit for 的问题（小白）

重修这门课，感谢指教！
Private Sub Command1_Click()
Dim a() As Integer
Dim i As Integer, j As Integer, n As Integer
Dim p As Integer, k As Integer
ReDim a(1): n = 1
Randomize
a(1) = Int(Rnd * (99 - 10) + 1) + 10
Do
p = Int(Rnd * (99 - 10) + 1) + 10
For i = 1 To UBound(a)
For j = 2 To Sqr(p)
If a(i) Mod j = 0 And p Mod j = 0 Then Exit For
Next j
If j <= Sqr(p) Then Exit For '这个步骤？？
Next i
If i > UBound(a) Then
n = UBound(a): k = n + 1
ReDim Preserve a(k)
Do While p > a(k - 1)
a(k) = a(k - 1)
k = k - 1
If k = 1 Then Exit Do
Loop
a(k) = p
End If
Loop Until UBound(a) = 10
For i = 1 To 10
Text1 = Text1 & Str(a(i))
Next i
End Sub