在Rails中使用Prawn gem如何将表宽设置为100%？

我使用Prawn gem生成pdf表.我需要将表的宽度设置为100%.我怎样才能做到这一点？

这是我的slmun_pdf.rb

class SlmunPdf < Prawn::Document
  def initialize(slmunDbs, view, allcount)

    if slmunDbs.table_name == "schools"
      super(top_margin: 50)
      if slmunDbs.size != allcount
        @warn = " (Not all Schools)"
      else
        @all = " All #{slmunDbs.size} Schools"
      end
      text "Showing#{@all}", size: 18, style: :bold, align: :center, color: "636363"
      text "#{@warn}", size: 11, align: :center, color: "858585"
      @schools = slmunDbs
      @view = view
      school_list

    end


  end

  def school_list
    move_down 20
    table school_list_rows, :cell_style => { :font => "Helvetica", :size => 9, :border_width => 0.5, :borders => [:top, :bottom], :border_color => "B0B0B0", :text_color => "737373"} do
        self.row(0).align = :center
        row(0).background_color = 'A0B046'      
        row(0).text_color = "FFFFFF"
        self.row_colors = ["DDDDDD", "FFFFFF"]
        self.header = true
    end
  end

  def school_list_rows
    [["Name", "Contact", "Country", "Pre Registration", "Full Registration", "Assigned Countries", "Total Delegates"  ]] +
    @schools.map do |school|
      countries = ""
      len = school.countries.count
      school.countries.each_with_index do |country, index|
        countries << "#{country.country }"
         if index+1 != len
          countries << ","
         end
      end 
      [school.name, school.contact, school.country, @view.yesno(school.prereg), @view.yesno(school.fullreg), countries, school.delegates.size ]
    end
  end

end

现有的文件没有帮助.我可能会使用不同的方法？我是从rails cast中学到的!