分析句子的语法成分：It was not unti my third year in high school that

It was not unti my third year in high school that the possibility took hold.
直到我高三时这一想法才有了实现的可能.
not until.（直到.才)
it was.that...(强调句型）
两者合并就是：It was not until.that...(强调until 部分）
句子还可以写成非强调句型：It was not until my third year in high school did the possibility take hold.

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