after a while 不久,過一會兒 After a while,he was asleep.
in a while adv.過一會,過不久 once in a while 偶爾
She haves a headache once in a while
for a short while 暫時 短短一會兒 The road is closed to traffic for a short while.
區(qū)別：after a while 可以看做是個時間狀語是某一時間點 after + 一段時間 = 一段時間 + later
in a while 通常是 once in a while 的形式 表示not often
for a short while 相當于時間段,表示持續(xù)的過程