正是…
it is precisely X that …; pins the cause or the credit on one thing
Structure
正是 X ， （才） …
What it means
'It is precisely X that …': pins the cause, the credit or the identity on one thing. 正 adds 'exactly, none other than' to 是.
How it is built
正是 + X，(subject) + 才 + result: 正是因为有你们的帮助，我们才完成了这个项目 (it is only thanks to your help that we finished the project).
When to use it
Common frames: 正是因为…才…, 这正是…的原因, 正是他. 就是 does the same job in plainer, more spoken language.
Watch out
The natural partner of 正是因为 is 才, and 才 goes after the subject: ✗正是因为下雨，才比赛推迟了。 ✓正是因为下雨，比赛才推迟了。
Examples
正是那段很少出门的日子，让不少人第一次尝试了网购。
It was precisely those weeks of staying in that got many people to try online shopping for the first time.
正是因为有你们的帮助，我们才完成了这个项目。
It is only thanks to your help that we finished the project.
Learn this in Lesson 85 · HSK 6–7: 共同的记忆 (Shared memories, 2003–2022)
A dialogue, a reading, word cards with audio and a drill that uses it, in Learn Chinese with Bao. The first lessons of every level are free.
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