不知道你那些控件的名称,随便写一个程序供你参考,程序如下:
Private Sub Command1_Click()
Dim f$, c$, s$, jg$, p%
s = "电脑硬件电脑系统"
f = "电脑"
c = "计算机"
p = InStr(s, f)
Do While p <> 0
jg = Left(s, p - 1) & c & Right(s, Len(s) - p - Len(f) + 1)
s = jg
p = InStr(s, f)
Loop
MsgBox jg
End Sub