下列计算正确的是（　　）

国家统一实施的所有适龄儿童、少年必须接受的教育，国家必须予以保障的公益事业是

下图为我国南方某区域等高线（单位：米）地形图，读图回答下列问题。

请根据要求改写下列句子，每空一词。
____ Susan has a good time on her birthday every year. (改为否定句)
Susan    ▲       ▲   a good time on her birthday every year.
____ Xiao Li paid more than 4,000 yuan for his new iPhone 4? (对划线部分提问)
   ▲       ▲   did Xiao Li pay for his new iPhone4?
____ The manager told them to be more creative in their work. (改为被动语态)
They    ▲       ▲   to be more creative in their work.
____ Some children are so young that they can’t tell the bad from the good. (保持句意基本不变)
Some children aren’t     ▲       ▲   to tell the bad from the good.
____ Rose went to the car exhibition yesterday. Danny went there, too. (保持句意基本不变)
  ▲   Rose    ▲   Danny went to the car exhibition yesterday.

在2011年5月15日进行的国际田联钻石联赛上海站中，首次尝试七步上栏的刘翔以13秒07创项目赛季最好成绩夺冠。他采用蹲踞式起跑，在发令枪响后，右脚迅速蹬离起跑器，在向前加速的同时提升身体重心。如下图所示，假设刘翔的质量为m，在起跑时前进的距离s内，重心升高量为h，获得的速度为v，克服阻力做功为W_阻，则在此过程中                                                                              （    ）