1.a poster child for sth
(typical example)…的典型；…的模范
Zidane became the poster child for a whole generation of French-born youths of North African extraction.齐达内已成为在法国出生、有着北非血统的年轻一代的模范人物。
She's a poster child for free speech.她是言论自由的代表人物。
2.(who appears on posters)(出现在海报或广告上的)名人, 代言人
The current national poster child is a tiny, freckle-faced redhead.现在的那个全国广告代言人个头不高, 红头发, 脸上有雀斑。