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。
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。