一道初一英语同义句改写题.

问题描述:

一道初一英语同义句改写题.
He goes to study in America when he is nineteen.
He goes to study in America ( ) ( ) ( ) ( ) nineteen.
将上句改为下句,意思不变.一个括号内一个单词.

He goes to study in America (at) (the) (age) (of) nineteen.
at the age of=when he is