1. at a time每次，一次；在……期间
Let's attack one problem at a time.
咱们一次全力处理一个问题。
Beat in the eggs, one at a time
打入鸡蛋，一次一个。
Blend in the eggs, one at a time, beating well after each one.
一次一个地掺入鸡蛋，每放一个都充分打匀。
Add the cream a few drops at a time
每次加几滴奶油。
She ran for the staircase and down the steps, taking them two at a time
她跑向楼梯，一步两级地奔下台阶。
He does not paint for very long on any one painting, perhaps for two and a half hours at a time
他每幅画不会画很长时间，一次大概画两个半小时。
Speak one at a time. Don't make such a row.
一个一个说，别瞎（乱）吵吵。
Don’t all speak at once! One at a time .
不要同时说全部的事情。一次说一个事情。94年高考题。
Can I borrow two books at a time?
我可以一次借两本书吗？
Many alcoholics go on drinking sprees that continue for days at a time.
许多酒鬼一次要狂饮好几天。
He was able to spend only a few days at a time on the island
他每次去岛上都只能呆几天。
Customers are drawing in their horns at a time of high interest rates.
消费者在高利率时期都在紧缩开支。《柯林斯高阶英汉双解学习词典》
She brought her children into the world at a time when obstetrics was a primitive art.
她生孩子的时候，产科学还是一门原始医术。
Over a lecture course he regularly showed undergraduates works of impressionism for two seconds at a time.
在一门课上,他定期向本科生展示印象派作品,每次两秒钟。
六级真题- 2015年
The revisions come at a time when green marketing is on the rise.
这个修订是在绿色市场兴起时出现的。
六级真题- 2016
2.at one time一度，从前（有个时期），过去某个时间
相当于at an unspecified time in the past
At one time I lived in Japan.
我曾一度住在日本。
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。
Criminals could at one time be sentenced to penal servitude.
曾经有个时期，罪犯可以被判服劳役刑。
At one time, walking across the room took all her strength
曾经有段时间她得费尽全力才能从房间一头走到另一头。
At one time the schools were mainly attached to the church.
这些学校曾一度归教会主管。
At one time 400 men, women and children lived in the village.
曾经有400个男人、女人和孩子居住在村子里。
All of them were French possessions at one time or another.
它们都曾是法国的领地。
All of these industries have at one time or another been linked to cancer.
所有这些产业都曾在不同时期与癌症有过联系。
at one time也可以表示“每一次”，如：
The fish lay thousands of eggs at one time.
这种鱼一次产卵数千个。《牛津高阶英汉双解词典》
3.at the time 当时，那个时候
Jackson called at the office this afternoon, but I could not see him, as I was engaged at the time.
杰克逊今天下午到办公室来了，但我当时正在忙，没能见他。
It seemed like a good idea at the time.
当时这主意好像不错。
There was a war on at the time.
当时正值战争。
The fashion at the time was for teaching mainly the written language.
那时教学时兴的主要是书面语。
I was pregnant with our third child at the time.
当时我正怀着我们的第三个孩子。
To my certain knowledge he was somewhere else at the time.
我敢肯定他当时在别处。
I was still in short trousers at the time.
我那时还在穿着短裤呢。
Nobody had much money at the time and I was no exception.
那时候谁都没有很多钱，我也不例外。
I felt he was wrong, although I didn't say so at the time.
我觉得他错了，不过我当时没有说出来。
The religious climate at the time was uncongenial to new ideas.
当时的宗教气候容不得新思想。
Fax machines were a wonderful invention at the time.
传真机在当时是一项了不起的发明。
No objections were raised at the time.
当时没人提出异议。
I was on picket duty at the time.
当时我正执行罢工的纠察任务。
I was out of work at the time
那时我失业了。
Many technical experts at the time had doubts about the technology.
当时，许多技术专家对那种工艺抱有疑问。
At the time we'd really nothing to tell the police.
当时我们真的没有什么能跟警方说的。
I was angry at the time but we had a good laugh about it afterwards.
我当时很生气，可后来却又觉得十分可笑。
It seemed like a good idea at the time, and then it all went horribly wrong.
那在当时似乎是个好主意，但后来却铸成大错。
词汇积累
attack [əˈtæk]
n.
袭击;攻击;(在战争中使用武器的)进攻;(口头和书面的)抨击，非难;抑制;发作，侵袭;（情感的）一阵突发;（病、虫等的）损害，伤害;进攻队员;（队员等的）进攻
v.
袭击;攻击;(在战争等中使用武器)进攻;抨击;非难;侵袭;奋力处理
blend [blend]
v.
(和某物)混合;融合;掺和;(使)调和;调制
n.
(不同类型东西的)混合品;混合物;(不同事物的)和谐结合;融合
row [roʊ , raʊ]
n.
一行;一排;一列;(剧院、电影院等的)一排座位;(编织中的)针行，一整行;严重分歧;纠纷;吵架;争吵;大的噪音;划船（时间）
v.
划(船);划船送(某人);吵架;大声争辩
alcoholic [ˌælkəˈhɑːlɪk]
adj.
酒精的;含酒精的;饮酒引起的
n.
酒精中毒者;嗜酒如命者;酒鬼
spree [spriː]
n.
狂欢；(常指过分)玩乐，作乐;纵乐;一阵，一通(犯罪活动)
obstetric [əbˈstɛtrɪk]
adj.
产科的
obstetrics [əbˈstetrɪks]
n.
产科学
primitive [ˈprɪmətɪv]
adj.
原始的;远古的;人类或动物发展早期的;发展水平低的;落后的;原始本能的
n.
文艺复兴前的艺术家(或作品);原始派画家(或作品)
penal [ˈpiːnl]
adj.
惩罚的;刑罚的;应受刑罚的;严重的;严厉的
servitude [ˈsɜːrvɪtuːd]
n.
奴役(状况);任人差遣(的状况)
exception [ɪkˈsepʃn]
n.
例外;一般情况以外的人(或事物);规则的例外;例外的事物
attach[əˈtætʃ]
v.
贴上;重视;把…固定，把…附(在…上);认为有重要性(或意义、价值、分量等);(有时不受欢迎或未受邀请而)参加，和…在一起，缠着;（使）与…有联系；为…所有
uncongenial [ˌʌnkənˈdʒiːniəl]
adj.
不友善的;性情不相投的;不愉快的;令人紧张的;不适宜的;不适合的;不利的
picket [ˈpɪkɪt]
n.
纠察队;(罢工期间纠察妥协分子的)纠察员;罢工警戒;(军营的)警戒哨;警戒队;哨兵;(尤指栅栏的)尖木桩;尖板条
v.
在…外抗议;进行罢工纠察
afterwards [ˈæftərwərdz]
adv.
之后;后来;以后