1.()There are two possible explanations to ________ the change in speed，but we don‘t know which one is right.
2.()_________ for his help，we couldn‘t have overcome the difficulties.
B.Hadn‘t it been
C.Had it not been
3.()It was ________ for Jim to finish the test paper within an hour because there were too many new words in it.
A.out of question
D.out of the question
4.()It is in Iran ________ the family members participate in the wedding preparations.
5.()________ put down the receiver _______ the telephone rang again.
A.Scarcely had she .……than
B.Scarcely did she .……than
C.She scarce had .……than
D.Scarce had she .……than
6.()He had been interested in history since his childhood，so he specialized _______ history when he was in college.
7.()The meeting ended _________ his lecture on high education.
8.()_________，he was not able to work out the puzzle.
A.However he tried hard
B.Whatever he tried hard
C.However hard he tried
D.How hard he tried
9.()_________ such enormous danger，he still remained as calm as usual.
A.In the face of
B.In face of
C.In the face with
D.In face with
10.()This is one of the most wonderful songs______ I have ever heard.
Researchers have found that REM(rapid eye movement)sleep is important to human beings.Thistype of sleep generally occurs four or five times during one night of sleep，lasting five minutesto forty mimutes for each occurrence.The deeper a person‘s sleep becomes，the longer the periodsof rapid eye movement.
There are physical changes 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.
1.()According to the passage，how often does REM sleep occur in one night?B.Twice
C.Four or five times
2.()The word “deeper”in pagragraph 1 is closest in meaning to which of the following?
3.()Which of the following shows that a person is NOT dreaming in his sleep?
A.His eyes begin to move.
B.His bueathing becomes faster.
C.His heart rate increases.
D.His eyes stop moving.
4.()The subject of this passage is .
A.why people sleep
B.the human need for REM sleep
C.the characteristics of REM sleep
D.physical changes in the human body
Eating habits change from generation to generation.Before scientists learned about vitamins and other constituents of food，such as proteins and carbohydrates(碳水化合物)，people believed in eating large quantities of food and were not concerned so much about a balanced diet.A hearty eighteenth century meal could consist of as many as twenty courses and would probably knock out many of us today!The Romans were famous for their enormous feasts and insatiable appetites.
In the year 2020 people‘s eating habits may be just as surprising but in a very different sort of way.With a world-wide growth in population，food production will become exclusively mechanical and scientific.There may well be an end to food as we know it today.Meals，as we know them may become a thing of the past.Food constituents and vitamins may be taken in the form of capsules(胶囊)，tablets and pills.The thought of these highly artificial food constituents replacing present day foods may not be very attractive，but they may be the answer to food shortage and world famine.
5.()According to the passage，people in the eighteenth century .
C.had better appetites
D.believed in eating more
6.()The word “enormous”in the first paragraph is closest in meaning to .
7.()Which of the following may be the best answer to food shortage and world famine?
A.The discovery of proteins and carbohydrates.
B.The production of artificial food constituents.
C.People‘s concern of a balanced diet.
D.The invention of capsules，tablets and pills.
Today we do not measure the speed of computer functions in minutes，or in seconds，or even in hundredths(1/100)or thousandths(1/1000)of seconds.We measure the speed of computers in billionthsof seconds.We call one billionth of a second a nansecond.
Computers were not always so fast，of course.In fact，at one time，the human mind could perform calculations faster than a computer.Let us look briefly at the development of the computer.We will see that the Computer Revolution happened only when computers developed their incredible speed.
In 1833，Charles Babbage built his “analytical engine”，the first computing machine.His colleague，Augusta Ada，the Countess of Lovelace，continued Babbage‘s work.She became the first programmer in history.Fifty years later，Herman Hollerith designed a machine that counted automatically.This machine was used to count the number of people in the United States for the 1890 census.It used a system of punch cards.Hollerith’s company，by the way，eventually became IBM(International Business Machines)。
The first large digital computer was built by IBM in 1944.It was called the Mark I.Then in 1947，IBM built the Mark II.Today we cannot imagine how slow these computers were，just as we cannot imagine how fast modern computers were，just as we cannot imagine how fast modern computers are.These computers needed one or two seconds to perform one calculation.In these same years，electronic computers developed.They were much faster than the huge，slow Mark I and Mark II.ENIAC is the name of the first all-electronic computer，built in 1944 and 1945.The world was amazed to learn the speed of this computer：5，000 additions per second，and 300 multiplications per second.Today we smile at these “slow”speeds.
Then in 1960 the real“revolution”began with the introduction of integrated circuits.Today，thousands of transistor circuits can fit on one small silicon chip.As a result，we now measure the speed of computers in nanoseconds.
8.()According to the passage，which of the following is the most important feature of a modern computer?
A.Its small size.
B.Its analytical power.
C.Its incredible speed.
D.Its system of punch cards.
9.()What brought about the speed of computers in nanoseconds?
A.The invention of digital computer.
B.The introduction of integrated circuits.
C.The design of an automatic counting machine.
D.The founding of Hollerith‘s IBM.
10.()The best title for this passage would be ______.
A.The Computer and the silicon chip
B.The Computer Revolution：Birth of the Nanosecond
C.Five Thousand Additions in One Second
D.IBM：International Business Machines Corporation
When you make up your mind to buy a house，most of the things you are concerned with are practical，(1)deciding whether you can afford it or the house is too (2)the station.You do not usually get the chance to (3)out about the neighbors before moving house.Flats are on the whole worse (4)houses from this point of view，but we have been lucky.When the old lady in the flat (5)we had a little boy，she was worried.‘I hope he won’t make too much noise‘，she said .Fortunately，the man underneath us has a full-time (6)in the city，so he doesn’t hear Tom running up and down all day.His main interest is (7)the communal garden.He told us when we moved in that we were (8)for mowing the lawn once a month.The young couple who live on the same (9)as us are very friendly;their only fault is that they are very forgetful.The day we arrived，Joyce came to ask us if she could (10)a phone call to Dave at work.She had come out without her keys and couldn‘t get back into her flat.
D.the far distance
D.getting down to