素数：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
        ①       
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        ②       =" True" Then
List1.AddItem Str（i）
count =" count" + 1
End If
Next i
Label1.Caption = "素数共有" + Str（count） + "个!"
End Sub