'提供给考生的程序
Private Function isprime(a As Integer) As Boolean
    Dim flag As Boolean
    flag = True
    b% = 2
    Do While b% <= Int(a / 2) And flag
        If Int(a / b%) = a / b% Then
            flag = False
        Else
            b% = b% + 1
        End If
    Loop
    isprime = flag
End Function