—You’re late again. We for you since 8: 00 a. m. . —Sorry. An unexpected visitor came to see me.
He ____ his home for a week.
--What’s ___ population of China? --China has ____ population of 1.5 billion.
--what do you think of the film? ---_____?
Is ____ dangerous to swim in the river alone?
--___do you clean the reading room? ---Every two or three days.