She showed the visitors around the museum, the construction _____ had taken more than three years.
Some amazing people _______ our world for the better in the past 100 years.
_______ was a struggle for me to remember all the strange faces and new names.
Mountain climbing _______ be tiring and many people feel sick as the atmosphere gets thinner.
Now she is considering taking some weight-loss pills, _______ she thinks will help her become slim.
The _______ boy made the police and his family _______.