填空题
已知B的ASCII码为66，以下程序统计由键盘输入的字符串中各英文字母的使用次数
Dim pp (65 To 90)
For i = 65 To 90
pp(i) =0
Next
x$ = InputBox(" Enter a string", x$ )
x$ = UCase$ (x$)
For i = 1 To Len (x$)
n =Asc(Mid$ (x$, i, 1) )
If n＞= 65 And n＜ = 90 Then
{{U}} 【11】 {{/U}}
End If
Next
For i = 65 To 90
Ifpp(i)＞0Then
Print Chr$ (i) ; pp (i)
End If
Next