编写“进制加法”程序。程序运行时,在文本框Text1输入进制值n(2≤n≤10),在文本框Text2和文本框Text3分别输入两个n进制数,单击按钮Command1后在文本框Text4上输出两个n进制数相加后的结果。若输入的进制值n不在规定范围内,则直接结束程序,程序运行界面如图所示:

(1)代码“Command1.Caption="计算"”中的Caption是
_______ (选填:对象名/属性名/属性值/方法名)。
(2)为实现上述功能,请在划线处填入合适的代码。
(3)程序中加框处代码有错,请改正。
______Private Sub Command1_Click()
Dim n As Integer
Dim ret As String, a As String, b As String
Dim c As Integer, i As Integer, jw As Integer
n = Val(Text1.Text)
a = Text2.Text: b = Text3.Text
If n < 2 Or n > 10 Then End
If Len(a) < Len(b) Then
t = a: a = b: b = t
End If
For i = 1 To Len(a) - Len(b)

Next i
jw = 0
For i = Len(a) To 1 Step -1
c = Val(Mid(a, i, 1)) + Val(Mid(b, i, 1)) + jw
ret =
_____ & ret
________Next i
If jw > 0 Then
______Text4.Text = ret
End Sub