القطعه الثانيه
II. Read the following passage carefully, then answer the questions that follow.
Many people wonder: Why do we sleep? Why do we dream? They ask themselves the purpose, or reason. There are many theories, or opinions about this , but scientists don’t know if these ideas are correct.
One theory of sleep says that during the day, we need sleep to make new chemicals and repair, or fix, our bodies. This theory is called the “ Repair Theory”. One piece of evidence for this theory is that our bodies produce more of growth hormone while we sleep.
Another theory is that the purpose of sleep is to dream. Dreaming occurs only during one stage , or period, of sleep ( Rapid Eye movement- REM )sleep. REM sleep occurs about 90 minutes and last for about 20 minutes. Some scientists believe that REM sleep helps us to remember things, but others don’t believe and don’t agree.