Use such+adjective+noun instead of so+adjective
1) his eyes were so desperate.
he looked at you with such __
2) i couldn't sleep. my room was so stifling.
it was such __
3) i have never anyone so thin.
i have never seen such __
4) his hair was so red.
he had such __
5) the weather was so hot.
it was such __
6) he looked so pitiful.
he was such __

1) His eyes were so desperate.

He looked at you with such desperate eyes.

2) I couldn't sleep. My room was so stifling.

It was such a stifling room.

3) I have never anyone so thin.

I have never seen such a thin person.

4) His hair was so red.

He had such red hair.

5) The weather was so hot.

It was such hot weather.

6) He looked so pitiful.

He was such a pitiful man.