(1)
2 * 10^4 cm = 2 * 10^2 m = 2 * 10^-1 km = 2 * 10^(4+9-2) nm
(2) 40 mL = 40 * 0.01^3 L = 40 * 0.001^3 m^3
(3) 0.3 kg = 0.3 * 10^3 g = 0.3 * 10^-3 T
(4) 3.2 * 10^5 没有单位?