Population is increasing in that country in a geometric progression.

那个国家的人口正级数增。

The E optotype on the chart had 3 limbs of equal length.A regular geometric progression of optotype sizes and distribution was employed to arrange 14 lines with 4 optotypes on each line.

用三划等的E形视标，视标大小及用均匀的增率，每行视标数为4个，共14行，每两行视标变化进率为拶而。