Private Sub Command1_click()

Dim s as integer,I as integer

S=0

For i=1 to 20 step 3

      s=s+(-1)^i*i

Next i

Label1.caption=str(i)

Label2.caption=str(s)

End Sub

实现上述功能的VB程序如下，但横线处代码有错，请改正。

Private Sub Command1_Click()

    Dim a As String

    Dim x As Integer, s As Integer, k As Integer

    a = Text1.Text

    x = 1: s = 0: k = 0

    For i = 1 To Len(a)

        '如果输入的不是0到9的数字或者空格，则给出错误提示后结束子程序

        If (Asc(Mid(a, i, 1)) < 48 Or Asc(Mid(a, i,1)) > 57)  or(Asc(Mid(a,i,1))= 32)  then’{#blank#}1{#/blank#}Label1.Caption = "只能输入数字或空格"

            Exit Sub

        End If

        If Mid(a, i, 1) = " " Then

            s = s + Mid(a,x,i)’{#blank#}2{#/blank#}

            x = i + 1

            k = k + 1

        End If

    Next i

    Label1.Caption = "这" + Str(k) + "个数的和为:" + Str(s)

End Sub

a = 1

b = 0

m = a

x = m + b

b = b + 1

y = x + b

它的基本结构属于（   ）

a(1)=2

For i=2 to 7

a(i)=a(i-1)*2-1

Next i

i = 1 : j = 7

Do While i <= j

m =（i + j）\ 2

If a（m）= Key Then Exit Do

If Key < a（m） Then j = m - 1 Else i = m + 1

Loop

若key的值为15，则程序执行结束后，j的值为（  ）

k=0:s=0

Do While k<=10

s=s+1

k=k+1

Loop