—What does PM 2.5 mean?
—It's a professional ________ indicating the condition of air pollution.
A．term B．item C．number D．mark
It is no ________ pretending you did not know because everyone saw the whole accident.
A．use B．help C．time D．joke
—He has a lot of friends who have a lot in ________ common with himself.
—Indeed.Birds of ________ feather flock together.
A．the; / B．the; a C．/; a D．a; the
Finding information in today's world is easy.The ________ is how you can tell if the information you get is useful or not.
A．knowledge B．ability
C．competition D．challenge
Friendship is both ________ source of pleasure and ________ component of good health.
A．a; a B．/; / C．the; a D．a; the
As ______ mountains surrounding our village are turning much greener, they have become ________ home to a large number of wild animals.
A．the; / B．the; a C．/; a D．the; the
