vb 求助 急

Option Explicit
Dim a, b As Variant
Dim i As Integer
Dim c, d As Variant
Private Sub cmd1_Click()
cmd1.Enabled = False
cmd2.Enabled = True
cmd3.Enabled = False
cmd4.Enabled = True
a = Time
Lbl1.Caption = a
Timer1.Enabled = True
Timer2.Enabled = True
End Sub
Private Sub cmd2_Click()
cmd4.Enabled = False
cmd2.Enabled = False
cmd1.Enabled = True
cmd3.Enabled = True
Timer1.Enabled = False
End Sub
Private Sub cmd3_Click()
Timer2.Enabled = False
Timer1.Enabled = False
cmd4.Enabled = False
cmd2.Enabled = False
Lbl1.Caption = ""
Lbl2.Caption = ""
Lbl3.Caption = ""
End Sub
'cmd4按下时候标题变成“继续”
'再次按下cmd4的时候标题变成“暂停”
Private Sub cmd4_Click()
If i = 1 Then
cmd4.Caption = "继续"
i = 2
c = Time
Timer2.Enabled = False
Else
i = 1
cmd4.Caption = "暂停"