1.diary的基本意思是“日记,日记簿”,指一天不漏地,为个人而保留的,对每天发生的事情,尤其是不愿对他人讲的个人感想或隐私问题的记录,或者是用于记录这些事情的本子。diary引申可指“日程安排”。
2.diary是可数名词,其复数形式是diaries,但diary常常以单数形式出现。
3.diary常和动词keep连用表示“写日记”。
4.在表示“一则日记”时要用an entry of diary。

He wrote an entry of diary in his diary.他在日记簿上记了一篇日记。
I keep a diary of my daily activities.我把每天的活动都写入日记。
I keep a diary in English every day.我每天用英语写日记。
Have you been reading my diary again?你又在看我的日记了吗?
Did you write a diary while you were travelling in Europe?在欧洲旅行时你记日记吗?
I always have something interesting to write in my diary.我总有有趣的东西要写在日记本上。
She began to write in her diary.她开始在日记本上写起来。
I have a very full diary today.我今天的工作日程排得很紧。
“Can you come on Wednesday?” “I'll just look in my diary to see if I'm free.”“你星期三能来吗?”“我要看一看我的日程安排,看我有没有空。”

diary, journal
这两个词的共同意思是“日记”。其区别在于:diary通常指“一天不漏地”; journal则倾向于“札记”,不一定每天都写,也不像diary那样有很大的隐私性,它往往指“对日常琐事的客观记录”和“读书随笔”。例如:
The police got everything out of his diary.警察从他的日记中知道了一切。
For three months he had kept a journal.三个月来他写了一本札记。

1.你最好用英语写日记。
［误］  You'd better keep an English diary.
［正］  You'd better keep a diary in English.
［析］  “用…(文字)写日记”要用in。
2.我每天都写日记。
［误］  I note diary every day.
［正］  I keep a diary every day.
［正］  I write in my diary every day.
［析］  “写日记”要用动词keep或write,而不用note。

［词源］  ＜拉丁语diarium(每天钱和食物安排的记载)