sentences:  Many people rollerblade professionaly or just for fun.Unlike quad skates, which have two front and two rear wheels, inline skates typically have two to five wheels arranged in a single line.Some, especially those for recreation, have a rubber "stop" or "brake" block attached to the rear of one or occasionally both of the skates so that the skater can slow down or stop by leaning back on the foot with the brake skate.