day的形容词是daily。day作为可数名词，基本含义为“白天”、“一天”、“工作日”、“时期”、“一天的活动时间”；daily除了可作形容词之外，还可作名词和副词，基本含义为“每日的”、“日常的”、“按日的”、“每天”、“日报”、“仆人”。

day作为可数名词，意为白天;一天;一日;白昼;工作日;一天的活动时间;时期。

例句：The day should be mainly dry with sunny intervals.

白天大部分时间应无雨，间有阳光。

Well, that's my good turn for the day.

好啦，这就是我今天做的好事。

Installation of the new system will take several days.

新系统的安装需要几天时间。

You should not go out in the heat of the day.

你不应该在天最热的时候外出。

Teachers are up against some major problems these days.

老师们最近面临着一些重大问题。

There's always a lot of traffic at this time of day.

每天这个时候总是有很多来往车辆。

I can't remember his taking a single day off work.

我不记得他请过哪怕一天假。

How would you like to spend the rest of the day?

后半天你打算怎么过？

We've come a long way since the early days of the project.

这项目开始以来我们已取得很大进展。

1、作为形容词时，意为每日的;日常的;每个工作日的;按日的。

例句：Invoices are signed on a daily basis .

发票按日签发。

They charge a daily rate.

他们按日收费。

The food queues have become a daily occurrence across the country.

排队购买食品的长龙已成了全国各地每日可见的景象。

It is impossible to live without some daily ruffles to our composure.

我们日常的平静生活免不了会遇到一些波折。

Daily parking costs follow a similar pattern.

按日计费的停车成本排名与此相似。

2、作为副词时，意为每日;每天。

例句：The machines are inspected twice daily.

机器每日检查两次。

Cathay Pacific flies daily non-stop to Hong Kong from Heathrow...

国泰航空公司每天都有从希思罗机场直飞香港的航班。

The food queues have become a daily occurrence across the country.

排队购买食品的长龙已成了全国各地每日可见的景象。

The castle is open daily from May to October inclusive.

这个古堡从五月起每天开放，直至十月底。

3、作为名词时，意为(除星期日外每日发行的)日报;(不寄宿的)仆人。

例句：The story was in all the dailies.

这则新闻刊登在所有日报上。

Copies of the local daily had been scattered on a table.

几份当地的日报散放在桌子上。

Pictures of the suspect were published in all the daily papers.

嫌疑人的照片刊登在各家日报上了。

Prospective buyers should study the small ads in the daily newspaper.

打算购物的人应该研究研究日报上的小广告。