—What do you often do ______ classes?—We often do eye exercises, do some running or talk with our friends.
---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.
—Could you post the letter for me? —_______________
—How do you like the book? —________________