【词组解析】
1. at a loss 茫然，不知所措
 （1）He found himself at a loss for words of consolation. 他简直想不出安慰的话来。
 （2）Mary is at a loss what to do next. 玛丽不知道下一步该做什么。

2. at a time 依次，逐一，每次
 （1）Hold the ladder tightly and move up a rung at a time. 抓紧梯子一级一级地往上爬。
 （2）Is there room for two people at a time to pass in? 这空间是否能使两人同时进入?
拓展：辨析 at the time;at that time;at one time;at a time
（1）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。
（2）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.
（3）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。
（4）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。

3. at all costs 不惜一切代价
  （1）We are determined to defend our motherland at all costs. 我们决心不惜任何代价保卫祖国.
  （2）We must finish the work at all costs before midnight. 无论付出什么样的代价,我们必须在午夜前完成这项工作.

4. at all events 不管怎样,无论如何
  （1）At all events, we can't make things worse than they already are. 在任何情况下我们都不会把事情搞得比现在更糟.
  （2）He is not clever, but at all events he works well. 他并不聪明, 但不管怎样他做得很好.

5. at all times 随时,总是
 （1）One can't completely govern one's thoughts at all times. 人不能始终控制得住自己的思想.
 （2）Firemen are ready at all times for a sudden turnout. 消防队员时刻准备着紧急出动。

【练习】
英译中：
（1）These troubles came along all at the same time that I was at a loss.
（2）He tore up the stairs two steps at a time.
（3）The women's volleyball team put up a desperate fight to win the world championship at all costs.
（4）I will come at all events.
（5）Doctor Liu is on call at all times.