1.today用作不可数名词时,意思是“今天”,只指白天,不指黑夜。一般用作主语,用作定语时多用其所有格。today还可作“现在,当代”解。
2.today等于on this day,故其前不可再加介词on。

here today and gone tomorrow
(指人)飘浮不定; 短暂 ephemeral〔present〕 for only a short time
It's difficult to find a window cleaner who will call regularly—they all seem to be here today and gone tomorrow.要找一个能定期上门来擦窗户的人很难——他们似乎都是些行踪不定的人。

I have finished my work for today.我已完成了今天的工作。
It's only three days from today.从今天算起来仅有三天。
We have today off for a holiday.我们今天休假。
Hａｖｅ ｙｏｕ read ｔｏｄａｙ'ｓ ｎｅｗｓｐａｐｅｒ?你看过今天的报纸了吗?
Wang Shuo is a writer of today.王朔是位当代作家。
He can present the Bible in today's language.他会用现代语言翻译《圣经》。
You'll be in a today where there is no yesterday or tomorrow to worry you.你将生活在今天这样的日子里,这里你没有昨天的烦恼,也没有明天的忧虑。

正如我在今天电话里对你说的那样,我没能获得签证。
［误］  As I told you in our today's telephone conversation,I have failed to get the visa.
［正］  As I told you in today's telephone conversation,I have failed to get the visa.
［析］  在today's, yesterday's 等构成的名词词组前不能再用限定词(包括物主代词)。

1.today用作副词时,表示“在今天,在今日”,只指白天,不指晚上,没有比较级和最高级。today还可表示“现今,在当代”。
2.today用在间接引语中,应改为that day。
3.today next week〔month,year〕表示“一周,一月或一年后的今天”。

用作状语
He has a headache and isn't feeling communicative today.他今天头痛,不爱说话。
Charles seemed very cool towards me today.查理今天对我似乎非常冷淡。
The young man was very short with him today.那青年今天对他很傲慢无礼。
The winds today will be light and variable.今天的风弱且风向不定。
It's questionable whether he'll come or not today.他今天来不来,还说不准。
The weather forecast says we'll have scattered showers today.天气预报报道今天将有阵雨。
She caught a bad cold yesterday and consequently was absent from school today.她昨天得了重感冒,所以今天没来上学。
Women today no longer accept such treatment.现代妇女不再认同这种待遇。
The Chinese people are very happy today.今天中国人民非常幸福。
In China today each couple is required to carry out a eugenic plan strictly.在今天的中国要求每对夫妇都要严格执行优生计划。
Life today would be very different without electricity.如果没有电,现今的生活可能完全是另一副样子。
The sports meet will be held a week today.运动会将在下周的今天举行。

1.今天下午没有课。
［误］  There will be no classes today afternoon.
［正］  There will be no classes this afternoon.
［析］  表示“今天下午”应该用this afternoon,不能用today afternoon。“今天上午”和“今天晚上”分别是this morning和this evening。但是,“今天夜里”是tonight。
2.他们说他们应该今天去看展览。
［误］  They said that they would go to the exhibition today.
［正］  They said that they would go to the exhibition that day.
［析］  today用作副词时,在间接引语中,应改为that day。

［词源］  ＜古英语to dæge(今天)