Are you a____(健康的) child? Bob, a 14-year-old boy, is very unhealthy. He likes to ____ (乘坐) his father's car to school. Sometimes he goes to school by ____(地铁).  He does exercise only ____ ( 一次) a week. He likes eating ____(垃圾) food very much. This week his parents are in Paris on ____ (度假). So he eats lots of unhealthy food every day. Now Bob is badly____(生病的) in hospital. The doctor says, “ You should ____ （经常）do exercise, and have a good ____(饮食) habits. It's ____ (重要的) for your health. 

实验需要木块进入不同的水平面有相同的初速度，则木块应从同一斜面____ 开始下滑．

函数y=﹣x²+1的单调递增区间为（　　）

世界上人口最多的大洲是（　　）