I've heard that if one is exposed to a lot of English as a child and inputs a lot of it when one's brain is highly flexible, then he/she can acquire English.
ご質問ありがとうございます。
"I've heard that if one is exposed to a lot of English as a child,"＝「子供のときに英語に沢山さらされて」
"and inputs a lot of it when one's brain is highly flexible,"＝「脳の柔軟性が高いときにそれらを多くインプットする」
"then he/she can acquire English."＝「そうすると、その子は英語を身に付けられる、と。」
ご参考に。
アメリカ合衆国 
