Why do we dream? Nobody knows, but everybody _____21_____. We dream during REM (rapid eye movement) sleep. In eight hours of sleep, people usually have four REM periods. But we _____22_____ very little. We usually remember only 20 or 30 seconds of REM sleep.
There are many ideas about dreams. Some psychologists believe we dream because we need a safe way to do things we can't do where we're _____23_____ . Some think we dream in order to work out our problems. _____24_____ believe dreams don't have any special meaning. They are simply thoughts that come to us when we _____25_____. Whatever you believe, dreams prove one thing—some people have wonderful imaginations. 【題組】21 (A)understands (B)dreams (C)sleeps (D)does