His son has poor eyesight because he plays _______ computer games.
Many _____ in ______ could hear no better than 65-year-old people, for they like pop music.
Mr. and Mrs. Green work in the hospital, but they have no children. So they belong to _____.
_____ is a program to help children’s education in poor areas.
About _____ of the world population is Chinese.
We should plant more trees on sides of the street.