time

time 的定语从句可以有四种形式(参见 way $^{1}$ ):

the time $\left\{ \begin{array}{l}when\\ at which\\ that\\ [ ] \end{array} \right\}$ she was here

但是,最常见的形式是零关系词(即不用任何关系词):

1. This is the time when you should get up. 是你该起床的时间了。

2. It's about a time when there were black slaves in North America. 讲的是美国北方存在黑奴的一段历史。

3. This was at a time when there was no radio, TV or cinema. 这是广播、电视和电影出现以前的情形。

4. What's the time (that) she normally arrives(at)? 她通常什么时候到达?

5. Do you remember the time (that) we all went to a night club? 你记得我们大家去夜总会的时间吗?

6. She's always busy doing something from the time [ ] she gets up in the morning till the time [ ] she goes to bed. 她一直很忙，从早上起床到上床睡觉。

选 B 是错误的, 应当选 A。

at a time 的意思是: “一次” “一下子”:

1. You can borrow only two books at a time. （你）一次只能借两本书。

2. He ran up the steps two at a time. 他一步两个梯级地往上跑。

3. Here are five points that help me learn — and remember — whole families of words at a time. 这里有五点要领可帮助我一下子学到——并记住——词的整个词族。

4. A whale may eat a ton of them at a time, and may enjoy four meals a day. 一头鲸鱼一次就可以吞食一吨这样的小鱼，一天可能要吃四餐。

at one time 的意思是: “一度” “过去曾经” “过去有个时期”:

1. At one time I lived in Japan. 我曾一度住在日本。

2. At one time most school teachers were men, but today there are more women than men. 以前中小学教员大都是男的，如今女的反比男的多了。