A strange thing happens to nearly everybody at night. They 61 the lights pull up the covers and close their eyes. After they sleep for six or seven 62 , they wake up again. It sounds very strange, doesn’t it?
Sleep puzzles(使困惑)science all the time. 63 and doctors would like to talk about why one can’t fall asleep. They are not so sure 64 causes sleep.
You will sleep the best both 65 you are in good health and when you don’t eat too much or too little. No worries and a comfortable place to sleep are 66 , too. They advise against two in one bed.
Strange things 67 during sleep. For example, you often move during your sleep. You would feel 68 if you didn’t move. You also 69 . Part of your brain(大脑)is still 70 when you dream.
Don’t worry if you dream. Some great stories and poems were finished while their writers were dreaming.
61. A. turn on B. turn off C. turn up D. turn down
62. A. seconds B. hours C. days D. months
63. A. Scientists B. Nurses C. Artists D. Inventors
64. A. why B. how C. which D. what
65. A. after B. when C. before D. until
66. A. pleased B. possible C. important D. funny
67. A. happen B. happens C. happened D. happening
68. A. hungry B. tired C. relaxed D. worried
69. A. sleep B. wake up C. think D. dream
70. A. busy B. asleep C. awake D. sleepy