VB程序求和

题目要求：'请不要更改源程序的结构，删除原题里的①、②、③。填写正确的代码，使程序完善(求1/1+1/2+2/3+…+21/34+…前10项的值)

Private Sub Command1_Click()
Dim s As Integer
Dim a As Integer
Dim b As Integer
Dim k As Integer
s = 0
a = 1
b = 1
For k = 1 To 10
s = s + a / b
a = ①
s = ②
b = ③
Next k
Print s

1 a=k-1

2 s=s

3 b=k