A、Children don’t get enough education in safety. B、Children are keen on dangerous games. C、The playgrounds are in poor condition

"Go to the playground and have fun," parents will often say to their kids. But they should remember playgrounds can be dangerous. Each year, about 200,000 children end up in hospital emergency rooms with playground injuries. Many injuries involve falls from too high equipment onto too hard surfaces. Nearly 70 percent of the injuries happen on public playgrounds. Recent studies show they may be badly designed, that protective services are inadequate and their equipment is poorly maintained. Parents should make sure that the equipment in the playground is safe and their children are playing safely.
   Last year, the national program for playground safety gave the nation’ s playgrounds a grade of "C" for safety after visiting more than 3000 playgrounds nationwide. Parents should watch closely. They should always be within shouting and running distance of their children. Young children don’ t understand cause and effect, so they may run in front of moving swings. They are also better at climbing up than getting down, so they may panic at the top of a ladder. It’ s important for children to know you’ re watching them. Once they feel that sense of security, that’ s when they can be creative.
Q:
19. What is the cause of playground injuries?
20. What should parents do to prevent playground injuries?