This is such a difficult question ______ none of us can answer.
Some people fear that ________ air pollution may bring about changes in ________ weather around the world.(2009·江西)
Sam has been appointed ________ manager of the engineering department to take ________ place of George.(2012·重庆)
Eggs are sold by ________ dozen while the meat is charged by ________ weight.
Last Sunday,we took ________ guided walk around by ________ signs of the famous town.
________ China's growth is not ________ threat to others.On ________ contrary, it will bring more opportunities to the world.