# File lib/linguistics/en.rb, line 1000
    def to_tens( tens, units, thousands=0 )
        unless tens == 1
            return Tens[ tens ] + ( tens.nonzero? && units.nonzero? ? '-' : '' ) +
                to_units( units, thousands )
        else
            return Teens[ units ] + to_thousands( thousands )
        end
    end