$mm^2$  

 $cm^2$  

 $m^2$  

 $km^2$  

$20m^2$

$24m^2$

$28m^2$

$30m^2$

$18cm^2$

$18m^2$

$17cm^2$

$17m^2$

$20m^2$

$22m^2$

$24m^2$

$26m^2$

卫生纸

报纸

方格纸

吸油纸

31 cm²

55 cm²

12 cm²

8 cm²