Structure:

Subject + 不是 + Adjective/Noun/Verb# 1+ 是 + Adjective/Noun/Verb#2

Meaning:

“不是…, (就)是…” (búshì…, (jiù)shì…) is used to clarify something about a certain noun. What’s being clarified can range from adjectives, verbs and even noun phrases

Examples:

1. 那 不是 一 个 困难，是 一 个 机会。

    Nà búshì yī ɡè kùnnɑn ， shì yī ɡè jīhuì

    That isn’t a difficulty, it’s an opportunity.