however , using this method to assess whether there is congruity between the two kinds of production also has its limitations : 1 -rrb- it can only reflect the speed of growth , but will not reveal the original levels ; 2 -rrb- it can not reflect the present levels attained by the two ; 3 -rrb- it will only reflect the ultimate production figures , but can not reflect the relationship between population and the various key elements of production -lrb- especially the various natural resources -rrb- and environmental resources .