A.Climbers develop skills useful in other activities. B.Climbers have the opportunity to be outside and enjoy the scenery. C.Climbing isnt as expensive as other sports. D.Learning to climb doesnt take a very long time,
【简答题】完形填空。 The population problem may be the __ 1 __ one of the world today. The world's population is growing __ 2 __ . Two thousand years ago, there were only 250 million people __ 3 __ the earth. Four h...