This contrasts with pre-metric units, which largely have names that do not relate directly to one another (e.g. inch, foot, yard, mile) and are related to one another by inconsistent ratios which must simply be memorised (e.g. 12, 3, 1760).
这与前公制（pre-metric）单位形成了鲜明对比，后者的名称大多不直接相关（例如英寸、英尺、码、英里），而且它们之间的比例不一致，必须直接记忆（例如12、3、1760）。