根据以下内容，回答下面试题。

　　Passage Three

　　Researchers have found that REM (rapid eye movement) sleep is important to human beings. This type of sleep generally occurs four or five times during one night of sleep lasting five minutes to forty minutes for each occurrence. The deeper a person's sleep becomes, ~the longer the periods of rapid eye movement.

　　There are physical charges in the body to show that a person has changed from NREM( non-rapid eye movement) to REM sleep. Breathing becomes faster, the heart rate increases, and, as the name implies, the eyes begin to move quickly,

　　Accompanying these physical changes in the body is a very important characteristic of REM sleep. It is during REM sleep that a person dreams..

　　第44题　According to the passage,, how often does REM sleep occur in one night? __________

　　A.Once　　B.Twice　　C.Four or five times　　D.Forty times

　　答案：C

　　第45题　The word "deeper" in Paragraph 1 is closest in meaning to which of the following? __________

　　A.heavier.　　B.louder.　　C.stronger.　　D.Happier.

　　答案：A

　　第46题　Which of the following shows that a person is NOT dreaming in his sleep?__________

　　A.His eyes begin to move.　　B.His breathing-becomes faster.

　　C.His heart rate increases.　　D.His eyes stop moving.

　　答案：D

　　第47题　The subject of this passage is__________.

　　A.why people sleep　　B.the human need for REM sleep

　　C.the characteristic of REM sleep　　D.physical changes in the human body

　　答案：C

　　根据以下内容，回答下面试题。

　　Passage Four

　　Man's first real invention, and one of the most important inventions in history, was the wheel. All transportation and every machine in the world depend on it. The wheel is the simplest yet perhaps the most remarkable of all inventions, because there are no wheels in nature-no living thing was ever created with wheels. How, then, did man come to invent the wheel? Perhaps some early hunters found that they could roll the carcass of a heavy animal through the forest on logs more easily than they could carry it. However, the logs themselves weighed a lot.

　　It must have taken a great prehistoric thinker to imagine two thin slices of log connected, at their centers by a string stick. This would roll along just as the logs did, yet be much lighter and easier to handle. Thus the wheel and axle came into being and with them the first carts.

　　第48题　The wheel is important because__________.

　　A.it was man's first real invention　　B.all transportation depends on it

　　C.every machine depends on it　　D.both B and C

　　答案：D

　　第49题　The wheel is called__________.

　　A.simple　　B.complicated　　C.strange　　D.unusual

　　答案：D

　　第50题　It was remarkable of man to invent the wheel because__________.

　　A.it led to .many other inventions　　B.man had no use for it then

　　C.there were no wheels in nature　　D.all of the above

　　答案：D

　　第51题　The wheel was probably invented by__________.

　　A.a group of early hunters　　B.the first men on earth

　　C.a great prehistoric thinker　　D.the man who made the first cart

　　答案：A