It turns out that if you start learning a language, a second language is where most of the work's been done, within the first few years of life you're fine.

如果你在出生的头几年里开始学习一门语言,非常努力地学习了第二门语言,那么你一切正常

耶鲁公开课 - 心理学导论课程节选

Can you give us some advice on learning a second language?

你能给我们一些关于学习第二语言的建议吗？

学第二外语的时候 - SpeakingMax英语口语达人