only once

The extreme isolation of these massive farms leaves them often unattended, and monitored only once or twice a year, which means if the livestock falls ill or requires assistance, it can be a long time for farmers to discover.

这些大规模的农场地处偏远，使得它们常常无人照管，每年只巡视一两次，这意味着如果牲畜生病或需要援助，农场主可能需要很长时间才能发现。

Only once in the past 30 years, 1997, has it been lower, and only marginally, the center said.

在过去30年间，只有1997年的怀孕率比现在略低。

If you store multiple Toot-O-Matic-generated tutorials on a single machine, the common files will be stored only once.

如果在单个机器上存储了多个Toot-O-Matic生成的教程，那么公共文件将仅存储一次。

The moon turns completely around only once during each circuit of the earth.

月球在绕地球转一周的同时,也正好自转了一周.

Some changes happen only once in a while, like an eclipse of the moon.

一些变化只有某个时候才会发生, 比如月食.

Only once in his life had Douglas permitted himself to lose control of his emotions.

道格拉斯一生中只有一次情绪失控。

Only once did we hit on a question which foxed one of the experts

我们只碰到过一个把一位专家也难住了的问题。

The selection criteria for the Hans Christian Andersen Prize, which can be awarded only once in life, include the aesthetic and literary qualities of writing and illustrating as well as the ability to see things from the child's point of view and the ability to stretch the child's curiosity and imagination.

一生只能获得一次的国际安徒生奖的选择标准包括：文学创作的美学与文学性、从孩子的角度看事物的能力以及孩子的好奇心和想象力的延伸能力。

He had seen her only once since the meeting.

自从那次会议以来,他只见过她一次.

a disposable nappy (= one that is made to be used once only)

一次性尿布

I don't know her well, I've only met her once or twice.

我跟她不很熟；我只见过她一两次。

I've only once seen him lose his rag.

我只见他发过一次脾气。

Only once we heard a gunshot a great way off, and supposed them to be hunting.

只有一次,我们听到很远的地方有一声枪响, 估计他们在打猎.

I've met her only once.

我只见过他一次.

You get a chance like this only once in a blue moon.

这种机会你是很难得到的.

I have crossed his path only once or twice in my life.

我这一生中只和他相遇过一两次.

I've as yet only once lighted on use of the word in the plural.

至今我只有一次发现这个词用复数形式.

Since the party she had only spoken to him once.

那次聚会以后，她只和他说过一次话。

I had been to Chrysler only once, when I was president of Ford.

我当福特公司的总裁时候,只去过克莱斯勒公司一次.

Objective To design and make the dispensing apparatus used only once, and remedy the deficiency of dispensensing with syringe.

目的设计和研制一次性配药器，以弥补用注射器配制药物的不足。

Some students might listen to a dialogue only once and understand it, so they can save time for doing other things.

有些学生可能听一次对话就听懂了，这样就可以节省做其他事情的时间。

This plant effloresces only once during its life cycle.

这植物在其生活史中只开花一次.

The government imposed a windfall tax (= a tax on profits to be paid once only, not every year) on some industries.

政府对某些行业征收暴利税。

If you can only exercise once a week, that's better than nothing.

即便是一个星期锻炼一次，也比完全不锻炼好。

He missed the target only once yesterday.

昨天他只有一次脱靶.

I saw her in a towering rage only once.

我只有一次见过她大发雷霆。

Opportunity knocks at the door only once.

机不可失,时不再来.

In a universe of ambiguity, this kind of certainty comes only once, and never again, no matter how many lifetimes human beings live.

在这个模棱两可的宇宙里，这种明明白白的事情只有一次，而且绝不会再来，无论人们能活多久也只有一次。

Only once during the lengthy discourse had the detective interrupted.

在冗长的谈话中,这位侦探只有一次打断了话头.

That implies that this latest sell-off can end only once it has tested whether 2002 was a false bottom-meaning stocks need to fall significantly from last month's low.

这意味着，只有当验证2002年是否是假底部后，最近的大跌才能停止&意指股价必须在上个月低点的基础上大幅下挫。