a. This craze started in Canada.
b. this was a method found by the Canadian ice hokey players who wanted to train in the summer.
c. the blades were changed for wheels because in the summer all the lakes and rivers were melted and there was no possibility to move on ice skates.
d. Roller-blading gives the opportunity to exercise the same muscles like ice-skates, but it can be used on the streets.
e. Roller bladers can reach speeds of up to 30 miles per hour.
f. Protective equipment includes a helmet, knee and elbow pads and special wrist bands.
g. In-line roller-skates can be used by everyone.