— Do you know the tower _____ in the heart of the city? — Do you mean the one _____ to the north of the city library?
She wondered __________.
---Do you know ________? --- I'm not sure. Maybe he is a businessman.
He is a friend ______ can help you in time of need.
The most important thing ______ we should pay attention to is the first thing ______ I have said.
This is the only one of these books that ______worth reading.