This is a prescribed course which spreads over two semesters.这是门两个学期学完的必修课.There are two semesters in a year.一年中有两个学期.Luckily, there are only two semesters a year.幸亏一年只有两个学期....

semesters的音标：...

n.（尤指美国的大专院校的）学期( semester的名词复数 )...