Надо ставить prepositions 1) Ms. Ballad substituted _____ our regular teacher

Надобно ставить prepositions
1) Ms. Ballad substituted _____ our regular teacher yesterday.
2) I can't distinguish one twin ____ the other.
3) Did you forgive him ____ lying to you?
4) Chris excels ___ sports.
5)Andrea contributed her ideas ___ the discussion .
6) The firefighters rescued many people ___ the burning building.