Some claim jogging is thought conducive； others insist the scenery relieves the monotony.（）

单项选择题Theauthor（）thattheearthweliveon（）.

A. is certain， can be saved by people’s action of recycling    
B. is not sure， can become better by people’s small gestures    
C. does not think， can be saved by what people are doing today    
D. is hopeful， will become a better place with people’s efforts

单项选择题Peopleareconcernedaboutthenaturalresourcesbecause（）.

A. they are being destroyed           
B. they cannot be replaced    
C. they are disappearing rapidly        
D. they are being replenished