When it______ air pollution, Beijing faces the three “C” s-----cars,coal and construction,which lead to Beijing's thick air pollution.
The boy and girl each _____ their own toys.
He is, however, one of those restless people who never ___ content with their present environment.
One or two days ____quite enough to complete the work. ___ you or he going to work with me?
. Your new clothes fit you, but mine_____ me.
. It is not I but you who ___ the first to run to the goal in the competition.