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实现该功能的VB程序段如下：；
Dim i As Integer
Dim s1 As String, s2 As String, ch As String, s3 As String
s1=Text 1. Text : s2=“” : s3=“”
For i=1 To Len(s1)’①
ch=Mid(s1,i,1)
If ch >= “a” And ch <= “z” or ch >= “A” And ch <= “Z” Then’②
s3=ch + s3’③
Else
s2=s2 + s3 +ch ’④
s3=“”
End if
Next i
Text 2. Text=s2
调试代码时发现无法实现程序功能，修改指定语句中和一条可使程序功能实现的是
| A．①改为For i=Len(s1) To 1 Step －1 |
| B．②改为If Not ((ch >= “a” And ch <= “z”) Or (ch >= “A” And ch <= “Z”)) Then |
| C．③改为s3=s3 + ch |
| D．④改为s2=ch + s3 + s2 |
同类型试题
y = sin x， x∈R， y∈[–1，1]，周期为2π，函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x， x∈[–1，1]， y∈[–π/2，π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2
y = sin x， x∈R， y∈[–1，1]，周期为2π，函数图像以 x = (π/2) + kπ 为对称轴
y = arcsin x， x∈[–1，1]， y∈[–π/2，π/2]
sin x = 0 ←→ arcsin x = 0
sin x = 1/2 ←→ arcsin x = π/6
sin x = √2/2 ←→ arcsin x = π/4
sin x = 1 ←→ arcsin x = π/2
