Rewrite the following sentences using present participle ( - ing), past participle or to infinitive : 1?

Rewrite the following sentences using present participle ( - ing), past participle or to infinitive : 1. Maxicorp was the only company which replied my letter. 2. Do you the man who is talking to my father? 3. Applications which were sent after 23rd will not be considered. 4. We have a lot of exercises which we have to do tonight. 5. Studies of her son are the most important things that she cares about. 6. The equipment which belongs to the club is insured. 7. George is the first person that we will interview.