The authors weren't sure why more girls were injured and speculated that perhaps more girls wear Heelys.
作者不能确定为什么女孩受伤的比较多，可能大部分的暴走族是女孩吧。
2
The Heelys company says the product is safer than biking, skateboarding, basketball, soccer and even tennis. But the other sports have more children participating. And is Heeling even a sport?