Ben's grandfather bought him a pair of roller skates.On Sunday,Ben and his father went to the park to play.Ben wanted to try his new shoes on.His father told him to be careful.Ben wore the shoes on.He ran very fast.His father was worried.There were some stones(石子) in front of him.Ben lost the balance(平衡).He fell off.His father sent him to the hospital.The doctor said that Ben's arm was broken.He couldn't go to school.He had to stay in bed.He was very sad.
( )1.What is the Chinese meaning of “roller skates”?