The best way to explore _______ countryside is on _______foot.
How long is it _____ we last spent the holiday in the countryside together?
_____air pollution getting worse, the government needs to come up with some effective measures to deal with it.
—What do you think of the equipment we’ve just bought?—You mean _____ over there? _____ is pretty good.
_____ an important role in a new movie, Andy has a chance to become famous.
—He is from America and majors in Chinese history in China.—_____.