Medel's experiments with peas had unique and important features, including the fact that （).

The author's experiments with different kinds of animals seem to prove that ______.

A．man and other animals have some similarities

B．man is the cruelest among animals

C．man is superior to other animals in some aspects

D．man is inferior to other animals in certain aspects

The author's experiments with different kinds of animals seem to prove that ______.

A．man and other animals have some similarities

B．man is the cruelest among animals

C．man is superior to other animals in some aspects

D．man is inferior to other animals in certain aspects

Running a fever was once thought to be the prerogative of warm-blooded creatures, whose internal temperatures are independent of the weather. But, as Matthew Kluger reported in "The Importance of Being Feverish" January 1976, lizards can also develop fevers, even though there is no question that they are cold-blooded. They raise their temperatures by moving into the sun or, in the case of Kluger's experiments, under a sun lamp. And it seems to do them some good. Sick lizards kept in cages at feverish temperatures fare much better than their counterparts in normal and cool environments.

Now ,fever has spread to invertebrates(无脊椎动物). Recent studies have shown that crayfish and scorpions can develop fevers. Crayfish injected with bacteria and scorpions injected with prostaglandins (前列腺素)swam and scuttled to hot areas. Prostaglandins are hormones thought to be instrumental in the development of a fever.

Evidence is also mounting that moderate fevers have their benefits, which might explain why the fever process is so widespread. Leukocytes, white blood cells that are active in fighting bacterial infections, are more mobile at febrile temperatures. And fevers reduce the amount of iron available to bacteria. That reduction, combined with high temperatures, has been shown to inhibit bacterial growth.

Which of the following best states the main idea of the passage?

A．Cold-blooded animals can develop fevers.

B．There are benefits to developing fevers.

C．Fevers inhibit bacterial growth.

D．Lizards can develop fevers.

The writer' s experiment shows that downshifting ______.

A．enables her to realize her dream

B．helps her mold a new philosophy of life

C．prompts her to abandon her high social status

D．leads her to accept the doctrine of She magazine

Laudenslager's experiment showed that the immune system of those rats who could turn off the electricity______.

A．was altered

B．was strengthened

C．was weakened

D．was not affected

阅读短文，回答 21～25 题：

第 21 题 The purpose of George Spilich's experiments is ________

A．to test whether smoking has a positive effect on the mental capacity of smokers

B．to show how smoking damages people's mental capacity

C．to prove that smoking affects people's regular performance

D．to find out whether smoking helps people's short-term memory

The writer\'s experiment shows that downshifting _______ .

A enables her to realize her dream

B helps her mold a new philosophy of life

C prompts her to abandon her high social status

D leads her to accept the doctrine of She magazine

The writer\'s experiment shows that downshifting _______ .

A enables her to realize her dream

B helps her mold a new philosophy of life

C prompts her to abandon her high social status

D leads her to accept the doctrine of She magazine

The purpose of George Spilich's experiments is______.

A．to test whether smoking has a positive effect on the mental capacity of smokers

B．to show how smoking damages people's mental capacity

C．to prove the smoking affects people's regular performance

D．to find out whether smoking helps people's short-term memory