     if evt.target
       $el = $(evt.target)
     else
-      $el = @$('.extra-buttons:last .btn-danger') # 假设最后一个删除按钮
+      # Assume the latest delete button
+      $el = @$('.extra-buttons:last .btn-danger')
     @undelegateEvents()
     if @options.allowBlank and @$el.children().length == 1
       el = $el.parents('.control-group').find(@subviewContainer).children()

    if childrenLength == 1 and @options.allowBlank
      @$('.extra-buttons .btn-primary').prop('disabled', false);
      conditionAvailabel = true
    if @options.allowBlank and @$el.find(@subviewContainer).children().length != 0
      @$('.extra-buttons .btn-danger').prop('disabled', false)
      conditionAvailabel = true
    if @options.limit and childrenLength == @options.limit
      @$('.extra-buttons .btn-primary').prop('disabled', true)
      conditionAvailabel = true
    if conditionAvailabel
      return

    @delegateEvents()

  clear: =>
    # Limit to only one child.
    child = $(@$('.control-group')[0]).clone()
    @$el.html(child)
    # Empty the child.
    @$('.control-group').find(@subviewContainer).empty()

  setOptions: (options) =>
