postal course的用法和樣例：
例句
- He is following a correspondence course in gardening for adults with comparative ease.
他正在上一個(gè)相對簡(jiǎn)單的園藝成人函授課程。 - A correspondence course is offered by mail, completed entirely by home study, often with one or two proctored, or supervised examinations.
函授課程是透過(guò)函件往返，學(xué)生完全是在家以自修方式完成，通常會(huì )有一或二次經(jīng)由學(xué)校監督進(jìn)行的考試。
