intermediate和medium比较像，mid和middle比较像。所以分两组来说。 按词性来看，就仅看它们的形容词（mid就是个词缀，之后再细说） 前一组指的是“高中低”“大中小”的“中”，表示程度，即somewhere between two extremes。 例如， intermediate course 中等课程， small and medium-sized enterprises 中小企业。 后一组呢 ...
middle school: 1) a school in Britain for children between the ages of 8 and 12; 2) a school in the US for children between the ages of 11 and 14. high school: 1) a school in the US and Canada for children of 14 or 15 to 18 years old; 2) used in the names of some schools in British form children from 11 to 18 years old.
