单项选择题
A. the difficulties of exercising B. why exercising is good for your health C．important information to know about exercising D. why people have some wrong ideas about exercising
A. walking is better than jogging B. working up a good sweat is the best way C. walking is one best exercise D. over-exercising is the best way
A. kind of weather pattern B. form of sea life C. species of tundra plant D. type of miniature penguin