Ответ:
- I bought a dress which my friend advised me to buy.
- We went to the party, which was very interesting.
- That is the village which we used to go to every summer.
- This is Mary Jones, from whom I’ve got a letter.
- I’ve found the key which I was looking for.
- This is the house which they bought last year.
- This is the actor whom I like very much.
В этих предложениях which относится к предметам, а whom — к людям в роли дополнения; в разговорной речи вместо whom часто употребляется who.
