C 生日 (anniversary of the) day of a person's birth

　birthday　的基本意思是“生日”，指每年一次的出生日期的纪念日，通常不表示出生的日期。但在美国填表时birthday可指出生年月日，即date of birth.

　celebrate ～　庆祝生日
　commemorate ～　纪念诞辰
　keep ～　过生日
　observe ～　过生日
　happy ～　生日快乐
　～ gift　生日礼物
　～ party　生日晚会
　～ present　生日礼物
　～ suit　赤身裸体
　at sb's ～　在（某人）生日那天
　for sb's ～　为了某人的生日
　on ～　在生日上
　～ of gunpowder　火药的发明之日

　Happy birthday to you!　祝你生日快乐！
　Your birthday is an annual event.　生日是一年一次的事。
　My wife's birthday is approaching.　我妻子的生日快要到了。
　Our birthdays are three days apart.　我们的生日前后相差几天。
　Another birthday has gone by, so now I'm fifteen.　又一个生日过去了，我现在15岁了。
　John's birthday did not seem complete without his father there.　没有他父亲在场，约翰的生日似乎少了点什么。
　His birthday occurs on July 4.　他的生日是7月4日。
　The company was celebrating its fiftieth birthday.　这家公司庆祝它诞生50周年。
　It was clever of her to think of his birthday.　能想到他的生日她真聪明。
　She was mad at her husband for forgetting her birthday.　她因为她的丈夫忘了她的生日而生气。
　For her birthday I bought her a bicycle.　为祝贺她的生日，我给她买了一辆自行车。
　I was not here on his birthday.　他生日那天我不在这里。
　I sent him a pencil box on his birthday.　我在他生日那天送他一只铅笔盒。
　Mary will become eligible to vote on her next birthday.　玛丽从下一个生日开始就有选举权了。
　At his birthday party, he blew out all the twenty candles at one time.　在生日晚会上，他一口气吹灭了二十根蜡烛。
　On the birthday party, she wore glad rags.　在生日晚会上，她穿上了漂亮的衣服。
　￡500 is quite a handsome birthday present. 　500英镑是很可观的生日礼物。
　It was sweet of you to send me a birthday present.　你给我送来了生日礼物，真太好了。
　We chose her a nice birthday present.　我们给她挑选了一件精致的生日礼物。
　The child was burning to see the birthday gift his grandma had sent him.　这孩子急切地要看看奶奶给他寄来的生日礼物。
　He brought me a lovely present on my sixteenth birthday.　我16岁生日那天，他给我带来了一件可爱的礼物。
　Aug. 15th. in 1980 is the country's birthday. 　1980年8月15日是这个国家的建国日。

1. 今天是我18岁生日。
　［误］ Today is my eighteen-year-old birthday.
　［正］ Today is my eighteenth birthday.
　［析］ “18岁生日”不可说eighteen-year-old birthday，而应说eighteenth birthday.
2. 请把你的出生日期填在表格里。
　［误］ Please put your birthday in the form.
　［正］ Please put your birth date in the form.
　［析］ birthday意思是“生日”，通常指从出生之日算起一年一度的周岁日，即anniversary of one's birth；而birth date指“出生的具体日期”，即date of birth. 一般说来， birthday是每年一次， birth date终生只有一次。