有一读者问：《许国璋英语》第二册第103页的with the Yellow Sea in between中，in between何意？做什么成分？ 它与副词between有何不同？
in between是一介词短语，由介词in和介副词between构成；它常用作状语，其意为“在二者之间”，再如：
(1)He left school at three, but didn't arrive home until six, so where was he in between ?
(2)There were two houses, with a narrow path in between .
(3)We have two lessons this morning, but there's some free time in between .
in between有时亦可用作定语和表语，如：
(4)The room was either extremely cold or hot, never anything in between . （在此用作定语）
(5)In between is a lake. （在此倒装句中用作表语）
介副词between的用法与in between相似，如：
(6)One town ends where the next begins and there's a road that runs between .
二者在意义上也几乎无甚区别，一般皆可互换使用。如细加揣摩，也许in between更加强调“二者之间或二者相隔的时间或空间”。
