She has to mop the kitchen floor at least once a day.

And they are only given food once a day.

而且它们一天只吃一次东西.

At least 60% of us now bathe or shower once a day.

现在我们当中至少60%的人每天淋浴或洗澡一次。

And close your eyes, And smile at least once a day!

然后闭上你的双眼, 记住每天至少微笑一次!

Walking at least once a day, each about half an hour.

每天至少散步一次, 每次大约半个小时.

It'should be done at least once a day, before brushing.

每天至少使用一次, 在刷牙之前.

Each student has to hand in a composition once a week.

每个学生每周必须交一篇作文.

In the ordinary course of events, I visit her once a week.

在一般情况下, 我每周去看她一次.

Slough off dry skin once a week.

每周除一次干皮.

Of course, I'll visit at least once a year, maybe more.

当然, 我最少每年会来拜访一次, 也许更多次.

Once a year a race is held for old cars.

每年举行一次旧汽车比赛.

Serpents cast their skin once a year.

蛇每年蜕一次皮.

The Moon reaches its absolute perigee once a year.

月球每年有一次达到它的绝对近地点.

Once a year they have to flush the city's sewers.

每年,他们都得冲洗一次城市下水道.

The farmers here sow once a year.

这里的农民一年播一次种子.

Once again there'stalk of very dark days ahead.

又有传言说以后的日子会非常艰难。

Once again he has broken his faith with them.

他又一次对他们不守信义.

Once again I warned her.

我又警告她一次.

All the sailors cheered once and again when they saw the Queen.

当水手看到女王时,欢呼声此起彼伏.

For even in Thessalonica you sent both once and again to my need.

16就是我在帖撒罗尼迦,你们也一次两次的,打发人供给我的需用.

Why did she do that experiment once and again?

为什么她再三地做那个实验?