采用拉锯式排序法对无序数组元素实现降序排序,即前一遍把最大的元素从右到左送到最左的位置,后一遍把最小的元素是从左到右送到最右的位置,实现该功能的 VB 程序段如下:

c = 1: s = 10
Do While c <= s
For i = s To c + 1 Step -1
If

Then
t = a(i - 1): a(i - 1) = a(i): a(i) = t
End If
Next i
For i =

If

Then
t = a(i + 1): a(i + 1) = a(i): a(i) = t
End If
Next i
c = c + 1
s = s - 1
Loop
上述程序段三个方框处的语句分别为( )
A.① a(i - 1) < a(i) ② c +1 To s – c ③ a(i) <a(i + 1) |
B.① a(i - 1) > a(i) ② c +2 To s – c ③ a(i) >a(i + 1) |
C.① a(i - 1) < a(i) ② c +1 To s – c-1 ③ a(i) <a(i + 1) |
D.① a(i - 1) > a(i) ② c+ 2 To s – c+1 ③ a(i) >a(i + 1) |