面积 + 体积单位换算

{"m2":{"label":"平方米","symbol":"m²","factor":1},"cm2":{"label":"平方厘米","symbol":"cm²","factor":0.0001},"ft2":{"label":"平方英尺","symbol":"ft²","factor":0.09290304},"mu":{"label":"亩","symbol":"亩","factor":666.6666667}}

{"km2":{"label":"平方千米","symbol":"km²","factor":1000000},"ha":{"label":"公顷","symbol":"ha","factor":10000},"in2":{"label":"平方英寸","symbol":"in²","factor":0.00064516},"yd2":{"label":"平方码","symbol":"yd²","factor":0.83612736},"acre":{"label":"英亩","symbol":"acre","factor":4046.8564224}}

{"m3":{"label":"立方米","symbol":"m³","factor":1},"l":{"label":"升","symbol":"L","factor":0.001},"ml":{"label":"毫升","symbol":"mL","factor":1.0e-6},"gal":{"label":"美制加仑","symbol":"gal","factor":0.003785411784}}

{"cm3":{"label":"立方厘米","symbol":"cm³","factor":1.0e-6},"ft3":{"label":"立方英尺","symbol":"ft³","factor":0.028316846592},"in3":{"label":"立方英寸","symbol":"in³","factor":1.6387064e-5},"ukgal":{"label":"英制加仑","symbol":"UK gal","factor":0.00454609},"bbl":{"label":"桶（石油）","symbol":"bbl","factor":0.158987294928}}