[thadajirajaras]

Are these correct?

I then you go to that room.
Learning then forgetting everything is bad.
Third molars are the teeth that rise then be pulled out.

[susan53]

1. Possible but strange. I'd say I'll go first and then you.
2. Perfect!
3. Some of the vocabulary is wrong and so is some of the grammar, but the use of then is possible : The third molars are the teeth which come through and then have to be pulled out.