The mechanisms by which parasites can survive in immune hosts are：

Which of the following statements can you infer from the passage?

A．The riders are competitive and fond of taking risks.

B．People except the riders show little interest in cyclo-cross.

C．Before 1967, amateur and professional classes had never been separated in competition.

D．Helpers are often hired by the riders.

The making of classifications by literary historians can be a somewhat risky enterprise. When Black poets are discussed separately as a group, for instance, the extent to which their work reflects the development of poetry in general should not be forgotten, or a distortion of literary history may result. This reminder is particularly relevant in an assessment of the differences between Black poets at the turn of last century (1900—1909) and those of the generation of' the 1920s. These differences include the bolder and more forthright speech of the later generation and its technical inventiveness. It should be remembered, though, that comparable differences 'also existed for similar generations of White poets.

When poets of the 1910s and 1920s are considered together, however, the distinctions that literary historians might make between "conservative" and "experimental" would be of little significance in a discussion of Black poets, although these remain helpful classification for White poets of these decades①. Certainly differences can be noted between "conservative" Black poets such as Countee Cullen, and Cluade McKay and "experimental" ones such as Jean Toomer and Langston Hughes. But Black poets were not battling over old or new styles; rather, one accomplished Black poet was ready to welcome another, whatever his or her style, for what mattered was racial pride.

However, in the 1920s Black poets did debate with specifically racial subjects. They asked whether they should only write about Black experience for a Black audience or whether such demands were restrictive. It may be said, though, that virtually all those poets wrote their best poems when they spoke out of racial feeling, race being, as James Johnson rightly put it "inevitably the thing the Negro poet knows best"②.

At the turn of the 20th century, by contrast, most Black poets generally wrote in the conventional manner of the age and expressed noble, if vague, emotions in their poetry. These poets were not unusually gift ed, though Roscoe Jamision and G. M. McClellan may be mentioned as exceptions. They chose not to write in dialect, which, as Sterling Brown has suggested, "meant a rejection of stereotypes of Nero life," and they refused to write only about racial subjects. This refusal had both a positive and a negative consequence. As Brown observes, "Valuably insisting that Negro poets should not be confined to issues of race, these poets committed (an) error.., they refused to look into their hearts and write. "These are important insights, but one must stress that this refusal to look within was also typical of most White poets of the United States at the time. They, too, often turned from their own experience and consequently produced not very memorable poems about vague topics, such as the peace of nature.

What is the author's attitude toward the classification as a technique in literary history?

A．Sarcastic.

B．Indifferent.

C．Cautious.

D．Critical.

The process by means of which human beings can arbitrarily make certain things stand for other things may be called the symbolic process.【31】we turn, we see the symbolic process【32】work. For example, stripes on the sleeve can be made to stand for military rank; crossed sticks can stand for a【33】of religious beliefs. There are【34】things that have not a symbolic value.

Almost all fashionable clothes are【35】symbolic. And we select our furniture to【36】as visible symbols of our taste, wealth, and social position. We often choose our houses on the【37】of a feeling that it "looks well" to have a "good address". We trade in perfectly good cars for【38】models not always to get better transportation,【39】to give evidence to the community that we can【40】it.

I once had an eight-year-old car in good running condition. A repairman, who knew the condition of the car, kept【41】me to trade it【42】a new model. "But why?" I asked, "The old car's in【43】still." The repairman answered scornfully, "Yeah, but all you've got is transportation."

Such complicated and apparently【44】behavior. leads philosophers to【48】over "Why can't human beings live simply and naturally?"【46】the complexity of human life makes us look enviously at the relative simplicity of such lives as dogs and cats lead.

Simply, the fact that symbolic process makes complexity possible is no【47】for wanting to【48】to a cat existence. A better【49】is to understand the symbolic process【50】instead of being its victims we become, to some degree at least, its masters.

(31)

A．Whichever

B．Whatever

C．Everywhere

D．However

The theme of the second last paragraph is why the perennials can survive as plants for several years.

A．Right

B．Wrong

C．Not mentioned

The theme of the second last paragraph is why the perennials can survive as plants for several years.

A．Right

B．Wrong

C．Not mentioned

The theme of the second last paragraph is why the perennials can survive as plants for several years.

A．Right

B．Wrong

C．Not mentioned

Even plants can run a fever, especially when they are under attack by insects or disease. But (1)_____ humans, plants can have their temperature (2)_____ from 3,000 feet away—straight up. A decade ago, (3)_____ the infrared scanning technology developed for military purpose and other satellites, physicist Stephen Paley (4)_____ a quick way to take the temperature of crops to determine (5)_____ ones are under stress. The goal was to let farmer (6)_____ target pesticide spraying (7)_____ rain poison on a whole field, which (8)_____ include plants that don't have the pest problem.

Even better, Paley's Remote Scanning Services Company could detect crop problem before they became (9)_____ to the eye. Mounted on a plane flown at 3,000 fee (10)_____, an infrared scanner measured the heat emitted by crops. The data were (11)_____ into a color-coded map showing (12)_____ plants were running "fevers". Farmers could then spot spray, using 50 to 70 percent less pesticide than they (13)_____ would.

The bad news is that Paley's company closed down in 1984, after only three years. Farmers (14)_____ the new technology and long-term backers were hard (15)_____. But with the renewed concern about pesticides on produce, and refinements in infrared scanning, Paley hopes to (16)_____ into operation. Agriculture experts have no doubt about the technology works. "This technique can be used (17)_____ 75 percent of agricultural land in the United States", says George Oerther of Texas A＆M. Ray Jackson, who recently retired from the Department of Agriculture, thinks (18)_____ infrared crop scanning could be adopted by the end of the decade. But (19)_____ Paley finds the financial backing (20)_____ he failed to obtain 10 years ago.

A．as

B．with

C．like

D．unlike

Children at Crown Lane school think that

A．the mediators are good.

B．the mediators can solve any problem.

C．teachers don't like the mediators much.

Even plants can run a fever, especially when they are under attack by insects or disease.But【21】______ humans, plants can have their temperature 【22】______ from 3,000 feet away— straight up. A decade ago, 【23】______ the infrared(红外线的)scanning technology developed for military purpose and other satellites, physicist Stephen Paley 【24】______ a quick way to take the temperature of crops to determine 【25】______ ones are under stress. The goal was to let farmer 【26】______ target pesticide spraying 【27】______ rain poison on a whole field, which 【28】______ include plants that don't have the pest problem.

Even better, Paley's Remote Scanning Services Company could detect crop problem before they became 【29】______ to the eye. Mounted on a plane flown at 3,000 feet 【30】______ , an infrared scanner measured the heat emitted by crops. The data were 【31】______ into a color-coded map showing 【32】______ plants were running "fevers". Farmers could then spot spray, using 50 to 70 percent less pesticide than they 【33】______ would.

The bad news is that Paley's company closed down in 1984, after only three years. Farmers 【34】______ the new technology and long-term backers were hard 【35】______ . But with the renewed concern about pesticides on produce, and refinements in infrared scanning, Paley hopes to 【36】______ into operation. Agriculture experts have no doubt the technology works. "This technique can be used 【37】______ 75 percent of agricultural land in the United States," says George Oerther of Texas A&M. Ray Jackson, who recently retired from the Depart ment of Agriculture, thinks 【38】______ infrared crop scanning could be adopted by the end of the decade. But 【39】______ Paley finds the financial backing 【40】______ he failed to obtain 10 years ago.

【21】

A．as

B．with

C．like

D．unlike

Animals in the Desert

Some desert animals can survive the very strong summer heat and dryness because they have very unusual characters. The camel, for example, can(51)an increase in the temperature of its body and its blood of 9℃. In addition, it can drink an enormous amount of water at one time, then store sufficient water in its red blood cells and other parts of its body to supply its needs for two weeks or more. The kangaroo rat (长鼻袋鼠) ,on the other hand,(52)all the water it needs from water that it produces during respiration (呼吸). However, most animals need to(53)a fairly constant body temperature, and will die if it rises more than 5℃.(54),they need to find some way to avoid the strong sun rays. Nor can many animals either store or produce water in their bodies, as the camel and kangaroo rat can. So they must find ways to(55)water loss from their bodies to the lowest degree.

Because very few desert animals can survive the strong rays, the temperature, and the evaporation

(蒸发) rate(56)a typical summer's day, most of them are(57)during the night. Only after the sun has set does the desert come fully to life; The night is(58)cool, and the darkness provides(59),not only from the sun, but also from other animals and from the birds. So the coming of darkness is the signal(60)the large majority of animals and insects (昆虫) to continue their search for water and food. When morning comes, most of them seek shelter again: many go underground; nearly all find(61)shady and they can avoid the sun rays there.

For many kinds of insects, living in the desert is(62)than for animals. Like many desert plants, they have a waterproof skin which(63)water loss by evaporation. In addition, some insects spend all or most of their life below ground. Here, for most of the year at least, there is(64)wetness, and it is generally cooler than on the(65).

A．carry

B．bear

C．effect

D．delay