Allow three clear days for the letter to arrive.

信要整整三天才能寄到。

《牛津词典》

Sun clocks worked, of course, only on clear days; water clocks misbehaved when the temperature fell toward freezing, to say nothing of long-run drift as the result of sedimentation and clogging.

当然，太阳时钟只能在晴天工作；当温度下降到接近冰点时，水钟就会失灵，长期漂浮的东西因为下沉或堵塞而无法工作。

youdao

You have four clear days to finish this work.

你有四个整天可用来完成这项工作。

youdao

"Obviously we are disappointed with the events that have happened over the last couple of days, I've made that clear,".

VOA: standard.2009.09.05

If unfamiliar, these are the mechanical computer devices that you have to use to buy a ticket on the T these days and there was one of these really awkward but touching situations where it was clear that this woman had no idea, you know, what to do, how to get from here to here, and I could see her just staring at the turnstiles that you're supposed to go through to get into the subway.

如果不熟悉，这是机械计算机设备,当今你必须使用它们来买地铁票,它们实在是难操作的,这个令人同情的情况是,明显这位老太太不知道怎样操作，怎样从这一步到那一步,我看见她只是凝视着,地铁的栅门口。

哈佛公开课 - 计算机科学课程节选

These houses command sweeping views of the Aegean and, on clear days, other Cycladic islands.

WSJ: Community by Design | Architecture

It is also one of the sunniest cities in the United States, ranking in the top 10 for clear days.

BBC: Living in: San Diego

On the hundred or so clear days a year when its summit is visible, McKinley is one of the most awe-inspiring sights on the continent.

BBC: The train that takes on Alaska��s Mt McKinley