at the time,at that time,的区别

概要：．．．”短语。这时，它表示“在（某事态）发生的时候”或“在……的时代”。例如： Were you in San Francisco at the time of the big earth quake in 1989﹖ 1989年旧金山发生地震时，你在那里吗？ It happened at the time of King Alfred． 事情发生在阿尔弗雷德国王时期。  at that time 则通常指前文明确提到的某个时期、时候。通常其后不带“of．．．”短语。例如： In the 17th century much corn was grown in Tibet and Sichuan．At that time (＝At the 17th century) the land along the Changjiang River was becoming very crowded．  at one time＝during a period of time in the past意为“过

at the time; at that time; at one time; at a time
 at the time通常用于过去时句子中，指某件事情发生的“当时”、“那时”。例如：
Many people saw the strange thing happen at the time． 当时，许多人都看到了这件奇怪的事情的发生。
 有时，at the time的后面可接“of．．．”短语。这时，它表示“在（某事态）发生的时候”或“在……的时代”。例如：
Were you in San Francisco at the time of the big earth quake in 1989﹖
1989年旧金山发生地震时，你在那里吗？
It happened at the time of King Alfred． 事情发生在阿尔弗雷德国王时期。
 at that time 则通常指前文明确提到的某个时期、时候。通常其后不带“of．．．”短语。例如：
In the 17th century much corn was grown in Tibet and Sichuan．At that time
(＝At the 17th century) the land along the Changjiang River was becoming very crowded．
 at one time＝during a period of time in the past意为“过去有一段时期”，“曾经”。例如：
They used to be good friends at one time． 他们曾经是好朋友。
 at a time则意为“一次”，表示一个时间单位。它常与表示数量的词语连用，表示频率。例如：
Don’t speak all at once．One at a time, please． 不要同时一起说。一次只一个人说。
Take the medicine three times a day and three pieces at a time． 这些药每天服三次，每次服三粒。