Country life gives him peace and quiet, which is ______ he can’t enjoy while living in big cities.
He knows so much about Russia that he's universally acknowledged as a(n) _____ on Russian affairs.
The first few years in the 21st century ______ the rapid rise of China as a world economic power.
Visitors to the National Museum can avoid long lines at the ticket booths by purchasing tickets ____.
She told me that she would not go with us if it ____ the next day.
I know one of the things I was unsure about was _____ hard it would be to climb this mountain.