11. Sheila is a TV producer. I've just met her->Sheila , whom I have just met, is a TV producer
12.The treaty has been signed by the president. He took power last year
-> The treaty,which He took power last year, has been signed by the president
13.David is going to talk about careers. I'm sure you all know him
-> David, whom you all know, is going to talk about careers
14.Who lives in the house? It has a white door
-> Who lives in the house which has a white door?
15.We visited a patient. His eyesight had been restored by the surgeon
-> We visited a patient whose eyesight had been restored by the surgeon