[填空题] 9号道岔尖轨的长度为6.25m，扳道(转换)道岔的时间为2s，后续车组的速度为6m/s，则前后车组溜经分歧道岔(9号)时，应保持的最小间隔距离为( )m。

{{B}}Testing Baby’s Brain{{/B}}
As far as her friends and teachers are concerned, Ashdod is an ordinary, bright, playful 5-year-old girl. They might be surprised to learn that not long ago therapists(治疗专家) were fighting to keep her from suffering from autism (孤独症)--a brain disorder that afflicts one in 100 children, typically leaving them with lifelong difficulties in communicating, socializing and carrying out many basic tasks. Ashdod was lucky: when she was 10 months old, her parents became alarmed that she had little interest in looking them in the eyes, eating and moving from her back, and took her to the Mifne Center in Rosh Pinna, Israel, a clinic that focuses on children 5 months and older who show early warning signs of autism. The results of the Mifne treatment were shocking, recalls the girl’s mother, Tikva. "Now she goes to a regular school where she is the same sort of active, funny, normal child
A. it covers a wide range of symptoms
B. it is difficult to be distinguished from other diseases
C. its symptoms change with the growth of age
D. it needs cooperation from different fields in medicine