Question

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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.

Answer 1

答案：B;C;D;A
解析：

1．这是一道主旨题。从文章的第1自然段和最后的自然段可以得出答案。 　　2．这是一道细节题。从文章的第2自然段可看出。 　　3．这是一道细节理解题。从文章的第3自然段可以得出结论。 　　4．这是一道细节题。从文章的第5和第6自然段可以看出。