1.This isn't the train by which I normally travel.
2.The letter that i opened wasn't for me.
3.The reason why I didn't know was that no one had told me.
4.What we should do is ring the police.
5.I didn;t know the name of the man who helped me.
6.Rupert knows the family whose house is for sale.
7.Einstein, who failed his university entrance exam, discovered relativity.
8.The person we talked to were very friendly.
9.It's the President who makes the important decisions.
10.I can't find my diary which is a real nuisance.
11.Outside the door was a pair of boots covered in mud.
12.Lake Superior which lies on the US Canadian border is the largest lake in North America