Is there a certain cure ___ lung cancer yet?
No one really knows exactly when the first group of people arrived in ______ we now know as California.
Some experts think the wolfs team spirit for survival is ______ is needed in today's competitive culture.
Many experts believe that teachers' development is ______ the key to better education lies.
Great honors will be given to ______ have successfully rescued the victims of the earthquake.
The biggest surprise for John was ______ he was chosen as team captain.