10．
A．For example B．happen C．while D．over and over
E．medical F．On the other hand G．especially H．thoughts I．enough
Dreaming is an activity of the brain．It produces electrical waves which can be measured．You have dreams when brain waves are （51）G fast．
Everyone dreams．If you think that you never dream，you are wrong．Most of the time，we cannot remember our dreams．Some scientists say that we dream mostly about the （52）H and wishes that we try not to show to others．Others say that if dreaming is not strong（53）I，it is difficult to remember them anyway．
Most people cannot control their dreams，they just（54）B．Very few people have clear dreaming．They can control what takes place in their dreaming （55）C they are asleep．
Even blind people dream．They may see pictures of events that have happened to them before they became blind．（56）F，a person who was born blind does not see pictures in dreams，but they can hear，smell and taste in them．
People often have the same dreams （57）D again．They may be events in your life that have caused problems which you have not solved yet．Nightmares are dreams that are so terrible that you usually wake up．There is （58）E treatment（治疗）for nightmares．You can go to a doctor who tries to find out why you have nightmares and how to deal with them．
