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You are what you eat. This saying has provided scientists with clues(线索) about the diet of hominidsour early relatives of 3 million years ago.
Studying carbon atoms(碳原子) locked up in tooth enamel (珐琅质), two researchers argue against the widely held belief that hominids ate little more than fruits and leaves. Sponheimer and Julia Lee-Thorp of the University of Cape Town, South Africa, report their findings in Friday’s Science.
There aren’t many clues for us to know the life of early hominids. The shape of hominids’ teeth offered the first clues. Large and flatedged with thick enamel, they looked perfect for eating nuts and fruits, different from the sharp teeth one would want to tear into meat with. The first stone tools, which would help in eating meat, didn’t appear until about half a million years later.
Scientists have also found marks on hominids’ teeth with patterns very similar to those on the teeth of modernday fruit eaters. Sponheimer and Lee-Thorp tried a new method, looking at the chemical composition of the tooth enamel. They studied the enamel for the carbon-13. Animals that eat grasses have higher carbon-13 levels than those eating fruits and other plants.
What they found was that the teeth of the hominids had an in-between amount of carbon-13, which meant not only they were eating fruits, they were eating a lot of grasses, or animals eating grasses. The lower carbon-13 levels could also come from eating certain types of insects(昆虫).
But there are people who understand differently. Prof. Ungar of the University of Arkansas agrees the study offers new suggestions of hominid diet, but disagrees about the suggestion that meat could explain the lower carbon-13 levels.
One suggestion might be true though-take good care of your teeth. In 3 millon years, a scientist might be using them to figure out what you ate for dinner.
1.Which of the following can be the best title for the text?
[ ]
A.Protect Your Teeth
B.What the Hominid Ate
C.Where the Hominid Lived
D.The Formation of Tooth Enamel
2.Before the two scientists’ findings, most people thought that hominids ________.
[ ]
A.lived half a million years ago
B.used tools to dig grass
C.ate mainly fruits and leaves
D.had sharp teeth
3.The two scientists’ findings were mainly based on the study about ________.
[ ]
A.the shape of horninids’ teeth
B.the teeth marks of early fruit eaters
C.the grasses of 3 million years ago
D.the make - up of the tooth enamel
4.What is it that Prof. Ungar finds doubtful?
[ ]
A.Hominids possibly ate grass - eating animals.
B.Hominids probably had different diets.
C.Hominids were basically fruit-and grass-eaters.
D.Hominids had lower level of carbon-13 in their teeth.
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第一节
听下面5段对话。每段对话后有一个小题,从题中所给的A,B,C三个选项中选出最佳选项,并标在试卷的相应位置。听完每段对话后,你都有10秒钟的时间来回答有关小题和阅读下一小题。每段对话仅读一遍。
1.How long did the concert last?
[ ]
2.Where is the man?
[ ]
3.When did Peter set the world record?
[ ]
4.What will Sue do after supper?
[ ]
5.Why can't men do better in a computer company than women?
[ ]
A.Because they are too strong.
B.Because they are not so careful as women.
C.Because their hands are too big.
第二节
听下面5段对话或独白。每段对话或独白后有几个小题,从题中所给的A,B,C三个选项中选出最佳选项,并标在试卷的相应位置。听每段对话或独白前,你将有时间阅读各个小题,每小题5秒钟;听完后,各小题将给出5秒钟的作答时间。每段对话或独白读一遍。
听第6段材料,回答6~7题。
6.What is the wan doing now?
[ ]
A.She is looking for a new job.
B.She is thinking of whether to take the job or not.
C.She is struggling to get a new job.
7.Why does the man suggest the woman go to the joint venture(合资企业)?
[ ]
A.Because she will have a promotion(升职).
B.Because she will learn to work with others.
C.Because she will earn a lot of money.
听第7段材料,回答8~10题。
8.What is the relationship between the man and the woman?
[ ]
A.They are lovers.
B.They are teacher and student.
C.They are classmates.
9.Where did they probably meet?
[ ]
A.At the bookstore.
B.At the library.
C.In the classroom.
10.What do they think of Prof. Robinson?
[ ]
A.They think he is quite knowledgeable.
B.They don't like his class.
C.They don't know anything about him.
听第8段材料,回答11~13题。
11.What did the Browns go to the man's house for?
[ ]
A.They wanted to visit their old friend.
B.They wanted to rent a house.
C.They wanted to interview the man.
12.What kind of house were they looking for?
[ ]
A.Modern and comfortable.
B.Small but comfortable.
C.Nice and quiet.
13.What time would they probably move in?
[ ]
A.Around two in the afternoon.
B.About eight in the evening.
C.Around ten in the morning.
听第9段材料,回答14~16题。
14.What problem does the girl have in English?
[ ]
A.She worries about mistakes.
B.She is afraid to talk.
C.She simply says“yes”or“no”.
15.When does the dialogue take place?
[ ]
A.At the end of the term.
B.When they were having supper.
C.At the beginning of the term.
16.What are they talking about?
[ ]
A.How to make speeches in class.
B.How to make fewer mistakes.
C.How to learn writing by his will.
听第10段材料,回答17~20题。
17.What does the speaker mainly talk about?
[ ]
A.The history of cola.
B.Soft-drink production.
C.Using cola as a drug.
18.How was cola originally sold?
[ ]
A.As a soft drink.
B.As a medicine.
C.As a cooking oil.
19.Why does the speaker mention John S. Pamberton?
[ ]
A.He sold cola to doctors.
B.He was a drugstore clerk.
C.He developed cola as a drug.
20.How was the drug made into a soft drink?
[ ]
A.By mixing it with special oils.
B.By heating it.
C.By adding soda water.
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