① “0.1g” → ±0.04 → 0.06~0.14g

② “2g” → ±0.5 → 1.5~2.5g

③ “2.0g” → ±0.05 → 1.95~2.05g

④ “2.00g”→ ±0.005 → 1.995~2.005g

精密称重(千分之一);称定(百分之一)