課本中不會(huì)教你的[A]90　at the age of和by the age of

90　at the age of和by the age of

① at the age of意為“在……歲時(shí)”，表示一個(gè)時(shí)間點(diǎn)。

He began to study English at the age of three. 他在3歲時(shí)就開始學(xué)英語了。

She went abroad with her father at the age of ten. 她10歲時(shí)同父親一起去國外了。

② by the age of意為“在……歲之前”，表示截止到某一時(shí)間之前，如果by the age of在句中指過去時(shí)間，謂語動(dòng)詞要用過去完成時(shí)。

He had read many novels by the age of fifteen. 在15歲前他就讀過許多小說了。

By the age of ten，she had learned to play the violin. 在10歲前，她就學(xué)會(huì)拉小提琴了。