Now the air in our hometown is ___________ than it was before. Something must be done.
He __________ the book for ten years.
So far _____ people have visited the old city in Zhejiang.
---Have you ever _____ the Great Wall? ---Yes, I have.
---_____ riding your bike to the park? ---Good idea.
Liu Sanzi is _____ eight-year-old boy from village.