只能被1和它本身整除的自然数。要求编写VB程序找出任意两个整数之间中所有的素数及个数，程序运行界面如下图所示。
请根据算法将下列程序补充完整。
Function prime（a As Integer） As Boolean
Dim j As Integer
prime = True
j = 2
Do While prime And j <= a \ 2
If a Mod j = 0 Then
prime = False
Exit Do
End If
____
Loop
End Function
Private Sub Command1_Click（ ）
Dim i As Integer, a As Integer, b As Integer
Dim count As Integer
a = Val（Text1.Text）
b = Val（Text2.Text）
For i = a To b
If ____ = True Then
List1.AddItem Str（i）
count = count + 1
End If
Next i
Label1.Caption = "素数共有" + Str（count） + "个!"
End Sub
