one-track mind
noun uk/ˌwʌn.træk ˈmaɪnd/ us/ˌwʌn.træk ˈmaɪnd/
have a one-track mind 思维单一;考虑问题一根筋;思维偏狭
to think about one particular thing and nothing else
And no, Bill, I wasn't talking about sex - you have a one-track mind! 噢，不，比尔，我讲的不是性——你的思维太狭隘了！