What's the coolest kind of transportation（交通工具）for middle school students back from the winter holidays? A racing bike? A car? No. It's a special __1__ of shoe called Heelys（暴走鞋）. Heelys look just like common __2__ shoes, but they have a wheel hidden in the heel（鞋跟）.So instead of ___3__, kids can“fly” around in them.

　　“Wearing Heelys is fun and ___4___,”said Wu Peng,a boy who wore them on his ___5___ day back at No.6 Middle School in Beijing. Wu Peng said he loves the shoes so much that he wears them wherever he goes. Sometimes he even ___6__ his parents' car to the supermarket on his Heelys!

　　Other students think these are very cool, ___7___ some haven't been so lucky with their Heelys. It's reported that some ___8___ have fallen down while using these shoes, and some have been hurt.

　　“Heelys wheels are on the heels of the shoes, so it's ___9___ to fall,”said Liu Rui, a doctor at the Hong Kong International Medical Clinic,Beijing. Even ___10___ , Liu said,“Wearing Heelys for a long time could stop young people from developing their ankles（脚踝）and legs.”