Use a relative pronoun.
1. Sheila is a TV producer. I've just met her->Sheila, whom I've just met, is a TV producer.
2.The treaty has been signed by the president. He took power last year-> The treaty has been signed by the president who took power last year.
3.David is going to talk about careers. I'm sure you all know him-> David, whom I'm sure you all know, is going to talk about careers.
4.Who lives in the house? It has a white door-> who lives in the house which has a white door?
5.We visited a patient. His eyesight had been restored by the surgeon->we visited a patient whose eyesight had been restored by the surgeon.
6.The girls should go to the main office. Their names begin with the letters A-K->The girls whose name begin with the letters A-K should go to the main office.
7.The countries will not be helped. They have very large debts-> the countries which have very large debts will not be helped.
8.The people will be compensated. Their houses were damaged by the bomb-> the people whose house were damaged by the bomb will be compensated.
9.The shop will make a big profit. Its turnover is the largest->the shop will make a big profit which is turnover is the largest.
10.The players changed their shirts at half-time. Their shirts were dirty->the player whose shirts were dirty changed their shirts at half-time.
11. Professor Wilson is an excellent lecturer. He teaches Chemistry.-> professor Wilson , who teaches Chemistry , is an excellent lecturers
12.The man is a famous actor. You mer him at the party last night.->the man whom you met him at the party last night is a famous actor
13.There are some words. They are difficult to translate-> There are some words which are difficult to translate.
14.The student writes well. I read her composition-> The student whose composition I read writes well.
15.Jim's sister is a famous architect. You met her yesterday.-> Jim's sister, whom you met yesterday , is a famous architect