After a long day at work, nothing is better than a good (91) ! Just like on the Earth, in space an astronaut goes to bed at a certain time, then wakes up and prepares for work again. There are a few differences though. Space has no “up” or “down”, but it does have (92)

. As a (93) , astronauts are weightless and can sleep in (94) orientation. However, they have to (95) themselves so they don’t float around and bump into something. Space station crews usually sleep in (96) bags located in small crew cabins. Each crew cabin is just big enough for one person.

Generally, astronauts are scheduled for eight hours of sleep at the end of each mission day. (97) on the Earth, though, they may wake up in the middle of their sleep period to use the toilet, or stay up late and look out of the window. Different things such as excitement or (98) _____ can disrupt an astronaut’s sleep (99) . During their sleep period, astronauts have (100) having dreams and nightmares.

91.A. night’s sleeps B. sleep of night C. night sleep D. night’s sleep

92.A. microgravity B. gravity C. law of gravity D. none of gravity

93.A. product B. conclusion C. result D. reason

94.A. any B. quite C. no D. some

95.A. keep B. fix C. attach D. relate

96.A. sleeper B. slept C. sleep D. sleeping

97.A. Like B.Unlike C. Alike D. Liking

98.A. homesickness B. motion sickness. morning sickness D. sleeping sickness

99.A. example B. design C. pattern D. arrangement

100. A. presented B. showed C. described D. reported