課本中不會教你的[A]83　at a time和at one time

83　at a time和at one time

① at a time表示“一次，再次”。

She reviewed three lessons at a time. 她一次復習了三課。

He went up the stairs two at a time. 他一次邁兩個臺階。

② at one time表示“曾經(jīng)，有一段時間”，常同過去時連用。

At one time I worked in a middle school. 有一段時間我在一所中學工作。

Her mother was at one time a nurse. 她母親有一段時間當護士。