Environment can be divided into 、 、 and according to its spatial scale.

A.prostatic part

B.spermatic part

C.membranous part

D.pelvic part

E.spongy part

A、two

B、three

C、four

D、five

Passage V

An astronomy class is given the following facts about stellar evolution.

1. A star’s evolution can be divided into 3 stages: premain sequence (pre-MS), main sequence (MS), and post-main sequence (post-MS).

2. Gravity causes part of a cloud of gas and dust to collapse and heat up, creating a pre-MS star. The star’s hot dust and gas emit its energy.

3. A pre-MS star becomes an MS star when the star produces the majority of its energy by fusing hydrogen nuclei (protons) at its center to make helium nuclei.

4. An MS star becomes a post-MS star when the star expands in volume and produces the majority of its energy by fusing hydrogen to make helium in a shell surrounding its center.

5. The more massive a star, the more rapidly the star passes through each of the 3 stages of its evolution.Two students discuss the evolution of the Algol system—Algol A, a 3.6-solar-mass MS star; Algol B, a 0.8-solar-mass post-MS star; and Algol C, a 1.7-solar-mass MS star. (One solar mass = the Sun’s mass.) The 3 stars orbit a mutual center of mass, with Algol A and Algol B much closer to each other and to the center of mass than to Algol C.

Student 1

The 3 stars of the Algol system formed at the same time from the same cloud of gas and dust. Algol B, originally the most massive of the 3 stars, became a post-MS star and expanded in volume while Algol A remained an MS star. Because the matter in the outer parts of Algol B was more strongly attracted to Algol A than to the matter in the inner parts of Algol B, this matter flowed from Algol B to Algol A, and, over time, Algol A became more massive than Algol B.

Student 2

Algol B was not part of the original Algol system (Algol A and Algol C). Algol B and the original Algol system formed in different clouds of gas and dust at different times and moved in 2 different but intersecting orbits around the center of the galaxy. During a particular orbit,Algol B encountered the original Algol system at the intersection of the 2 orbits and became part of the Algol system.Algol B became a post-MS star while Algol A and Algol C remained MS stars. Algol B never lost mass to Algol A. Algol B was always less massive than Algol A.

Based on Student 2’s discussion, Algol B is part of the present Algol system because of which of the following forces exerted on Algol B by the original Algol system?

A.Electric force

B.Magnetic force

C.Gravitational force

D.Nuclear force

Ours is a society that tries to keep the world sharply divided into masculine and feminine, not because that is the way the world is, but because that is the way we believe it should be. It takes unwavering belief and considerable effort to keep this division. It also leads us to make some fairly foolish judgments, particularly about language.

Because we think that language also should be divided into masculine and. feminine we have become very skilled at ignoring anything that will not fit our preconceptions. We would rather change what we hear than change our ideas about the gender division of the world. We will call assertive girls unfeminine and supportive boys effeminate, and try to change them while still retaining our stereotypes of masculine and feminine talk.

This is why some research on sex differences and language has been so interesting. It is an illustration of how wrong we can be. Of the many investigators who set out to find the stereotyped sex differences in language, few have had any positive results. It seems that our images of serious taciturn(沉默的) male speakers and gossipy garrulous(饶舌的)female speakers are just that images.

Many myths associated with masculine and feminine talk have had to be discarded as more research has been undertaken. If females do use more trivial words than males, stop talking in mid-sentence, or talk about the same things over and over again, they do not do it when investigators are around.

None of these characteristics of female speech have been found. And even when sex differences have been found, the question arises as to whether the differences is in the eye or ear of the beholder, rather than in the language.

If males do not speak in high-pitched voices, it is not usually because they are unable to do so. The reason is more likely to be that there are penalties. Males with high-pitched voices are often the object of ridicule. But pitch is not an absolute, for what is considered the right pitch for males varies from country to country.

The passage implies that the author's attitude towards the division of feminine talk and masculine talk is______.

A．assertive

B．snobbish

C．approving

D．critical

Ours is a society that tries to keep the world sharply divided into masculine and feminine, not because that is the way the world is, but because that is the way we believe it should be. It takes unwavering belief and considerable effort to keep this division. It also leads us to make some fairly foolish judgments, particularly about language.

Because we think that language also should be divided into masculine and feminine we have become very skilled at ignoring anything that will not fit our preconceptions. We would rather change what we hear than change our ideas about the gender division of the world. We will call assertive girls unfeminine, and supportive boys effeminate, and try to change them while still retaining our stereotypes of masculine and feminine talk.

This is why some research on sex differences and language has been so interesting. It is an illustration of how wrong we can be. Of the many investigators who set out to find the stereotyped sex differences in language, few have had any positive results. It seems that our images of serious taciturn male speakers and gossipy garrulous female speakers are just that: images.

Many myths associated with masculine and feminine talk have had to be discarded as more research has been undertaken. If females do use more trivial words than males, stop talking in mid-sentence, or talk about the same things over and over again, they do not do it when investigators are around.

None of these characteristics-of female speech have been found. And even when sex differences have been found, the question arises as to whether the difference is in the eye or ear of the beholder, rather than in the language.

Pitch provides one example. We believe that males were meant to talk in low-pitched voices and females in high-pitched voices. We also believe that low pitch is more desirable. Well, it bas been found that this difference cannot be explained by anatomy.

If males do not speak in high-pitched voices, it is not usually because they are unable to do so. The reason is more likely to be that there are penalties. Males with high-pitched voices are often the object of ridicule. But pitch is not an absolute, for what is considered the right pitch for males varies from country to country.

The passage implies that the author's attitude towards the division of feminine talk and masculine talk is

A．assertive.

B．snobbish.

C．approving.

D．critical.

The world seems increasingly divided into those who favor genetically modified (GM) foods and those who fear them. Advocates assert that growing genetically altered crops can be kinder to the environment and that eating foods from those plants is perfectly safe. And, they say, genetic engineering—which can induce plants to grow in poor soils or to produce more nutritious foods—will soon become an essential tool for helping to feed the world's burgeoning population. Skeptics contend that GM crops could pose unique risks to the environment and to health—risks too troubling to accept placidly. Taking that view, many European countries are restricting the planting and importation of GM agricultural products. Much of the debate hinges on perceptions of safety. But what exactly does recent scientific research say about the hazards?

Advocates of GM, or transgenic, crops say the plants will benefit the environment by requiring fewer toxic pesticides than conventional crops. But critics fear the potential risks and wonder how big the benefits really are. "We have so many questions about these plants," remarks Guenther Stotzky, a soil microbiologist at New York University. "There's a lot we don't know and need to find out. "

As GM crops multiply in the landscape, unprecedented numbers of researchers have started fanning into the fields to get the missing information. Some of their recent findings are reassuring; others suggest a need for vigilance.

Every year U. S. growers shower crops with an estimated 971 million pounds of pesticides, mostly to kill insects, weeds and fungi. But pesticide residues linger on crops and the surrounding soil, leaching into groundwater, running into streams and getting gobbled up by wildlife. The constant chemical trickle is an old worry for environmentalists.

In the mid-1990s agribusinesses began advertising GM seeds that promised to reduce a farmer's use of toxic pesticides. Today most GM crops—mainly soybean, corn, cotton and canola—contain genes enabling them to either resist insect pests or tolerate weed-killing herbicides. The insect-resistant varieties make their own insecticide, a property meant to reduce the need for chemical sprays. The herbicidetolerant types survive when exposed to broad-spectrum weed killers, potentially allowing farmers to forgo more poisonous chemicals that target specific weed species. Farmers like to limit the use of more hazardous pesticides when they can, but GM crops also hold appeal because they simplify operations (reducing the frequency and complexity of pesticide applications) and, in some cases, increase yields.

But confirming environmental benefit is tricky. Virtually no peer-reviewed papers have addressed such advantages, which would be expected to vary from plant to plant and place to place. Some information is available, however. According to the U. S. Department of Agriculture, farmers who plant herbicidetolerant crops do not necessarily use fewer sprays, but they do apply a more benign mix of chemicals. For instance, those who grow herbicide-tolerant soybeans typically avoid the most noxious weed killer, turning instead to glyphosate herbicides, which are less toxic and degrade more quickly.

Insect-resistant crops also bring mixed benefits. To date, insect resistance has been provided by a gene from the soil bacterium Bacillus thuringiensis (Bt). This gene directs cells to manufacture a crystalline protein that is toxic to certain insects—especially caterpillars and beetles that gnaw on crops—but does not harm other organisms. The toxin gene in different strains of Bacillus, thuringiensis can affect different mixes of insects, so seed makers can select the version that seems best suited to a particular crop.

Defining the environmental risks of GM crops seems even harder than calculating their benefits. At the moment, public attention is most trained on Bt

A．Whether it is environmental-friendly.

B．Whether it is healthy to people.

C．Whether it will cause influences on surrounding lives.

D．Whether it is safe.

Documentary credits are separate transactions from the sales contract with which they are related and Letter of Credit can be divided into many kinds depending on the circumstance．A documentary credit may be available by payment，by negotiation or by acceptance．【S1】means that the nominated bank will pay the beneficiary the full amount due once he submits the contract documents required under the credit．Under a【S2】，the beneficiary is given double assurance of payment since the confirming bank has added its own undertaking to that of the opening bank．If a credit can be transferred by the original beneficiary to one or more parties，it is a【S3】．If a credit stipulated that its amount can be renewed without specific amendment to the credit being made，it is then a 【S4】．【S5】are those that cannot be amended or revoked without the consent of all the parties concerned．

【S1】

A．Confirmed credit

B．Payment credit

C．Negotiation credit

D．Acceptance credit

Documentary credits are separate transactions from the sales contract with which they are related and Letter of Credit can be divided into many kinds depending on the circumstance．A documentary credit may be available by payment，by negotiation or by acceptance．【S1】means that the nominated bank will pay the beneficiary the full amount due once he submits the contract documents required under the credit．Under a【S2】，the beneficiary is given double assurance of payment since the confirming bank has added its own undertaking to that of the opening bank．If a credit can be transferred by the original beneficiary to one or more parties，it is a【S3】．If a credit stipulated that its amount can be renewed without specific amendment to the credit being made，it is then a 【S4】．【S5】are those that cannot be amended or revoked without the consent of all the parties concerned．

【S1】

A．Confirmed credit

B．Payment credit

C．Negotiation credit

D．Acceptance credit