VB 做不来啊 `. 帮帮忙啦`

Dim min as Integer
Dim max As Integer
Dim avg as Integer

Dim a(19) as Integer
Dim i as Integer
Dim strinput as String

for i=0 to 19
strinput=inputbox("请输入一个数值")
if strinput<>"" and strinput <> vbnullstring and strinput<>vbnull then
a(i)=cint(strinput)
end if
next i

min = a(0)
max = a(0)
avg = a(0)

For i = 1 To 19
If a(i) > max Then max = a(i)
If a(i) < min Then min = a(i)
avg=avg + a(i)
Next i

avg=avg/a.ubound

Form1.print "最大值：" + CStr(max)
Form1.print "最小值：" + CStr(min)
Form1.print "平均值：" + CStr(avg)

Private Sub Command1_Click()
i = 2
a = CInt(InputBox("ÊäÈëµÚ1¸öÊý"))
Max = a
Min = a
Sum = a
Do While i <= 20
a