`3`. -> The food was so salty that we couldn't eat.

     -> It was such a salty food that we couldn't eat.

`4`. -> The steak was so bad that we couldn't eat.

    -> It was such a bad steak that we couldn't eat.

`5`. -> The water was so cold that the children couldn't swim in.

     -> It was a could water that the children couldn't swim in.

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- S + to be + so + adj + that + S + V

= S (đại từ nhân xưng) + to be + such + a/an + adj + N + that + S + V: quá ... đến nỗi

- Thì quá khứ đơn: S + was/ were + ...

- S + could (not) + V-inf: (không/có) thể làm gì