请哪位朋友解释一下以下这句英语句子后半句“butitwasn't--"的语法现象?TheideaofbecomingawriterhadcometomeoffandonsincemychildhoodinBellerille,butitwasn'tuntilmythirdyearinhighschoolthatthepossibil

Question

请哪位朋友解释一下以下这句英语句子后半句“but it wasn't--"的语法现象?
The idea of becoming a writer had come to me off and on since my childhood in Bellerille,but it wasn't until my third year in high school that the possibility took hold.

Answer 1

这是强调句,强调until .high school ,后面的that是引导词.