2. it is ... that it is ... since.

it is ... that . :
I told him the news after he had returned from Leningrad.
ߠ , .
It was after he had returned from Leningrad that I told him the news.
, , .

not until till:
We did not receive a letter from them until (till) May.
.
It was not until (till) May that we received a letter from them.
.

She did not learn the truth until (till) she returned home.
, .
It was not until (till) she returned home that she learned the truth.
, .

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