Mary is the only one of the teachers who ________ a little Chinese because she is one of my friends who ________ been to China.
Have you read the book ____ I lent to you?
Finally, the thief handed over everything ____ he had stolen to the police.
The foreign guests, ____ were government officials, were warmly welcomed at the airport.
This is the very letter ____came last night.
I know only a little about this matter; you may ask ____ knows better than I.