甲、乙两物体在同一直线上,同时由一位置向同一方向运动,其速度-时间图像如图所示,

题型:选择题

问题:

甲、乙两物体在同一直线上,同时由一位置向同一方向运动,其速度-时间图像如图所示,下列说法正确的是(    )

A.甲作匀加速直线运动,乙作匀速直线运动;

B.开始阶段乙跑在甲的前面,20s后乙落在甲的后面

C.20s末乙追上甲,且甲、乙速率相等

D.40s末乙追上甲

考点:v-t图像
题型:选择题

已知P(11,2)是圆x2+y2+2x-4y-164=0内一点,则过P点的所有弦中,弦长为整数的共有______条.

题型:选择题

Spanish explorers called them Las Encantadas, the Enchanted Isles, and Charles Darwin used his studies of the islands as the foundation for his theory of natural selection. The Galapagos are among the world's most important scientific treasures, a group of volcanic islands surrounded by deserted beaches and inhabited by unique varieties of giant tortoise, lizards, and birds.

Yet life on this United Nations world heritage site has turned sour. Battles have broken out between fishermen and conservationists. Ecuador, which owns the islands, has sent a naval patrol (海军巡逻队) to put down disturbances.

The controversial director of the Galapagos National Park—which controls 97 percent of Galapagos land and the reserve extending to 40 miles offshore—has been fired, while an air of uneasy tension hangs over the islands, as the islanders prepare for election when they pick their representatives in Ecuador’s national assembly.

“It’s a very tense situation,” said Leonor Stjepic, director of the London-based Galapagos Conservation Trust, which raises money to help projects on the islands. “We are watching it with concern.”

The violence has been triggered by an alarming growth in the islands’ population. Puerto Ayora, on Santa Cruz island, housed just 45 inhabitants in the 50s. Today there are more than 10,000, while the islands' total population is more than 19,000 and growing by 6 percent a year, despite recently introduced a law to limit waves of immigrants fleeing the poor areas of Ecuador for a life “in paradise (天堂)”. On top of this, more than 100,000 tourists visit the islands every year.

Such numbers have put the islands, special ecology under intense pressure. Conservationists backed by the Ecuador government, have replied by exercising strict controls to protect the islands* iguanas, blue-footed boobies, and giant tortoises.

These moves have angered many local people, however. They want to exploit (开发利用) the islands’ waters and catch its protected species of sharks, lobsters and sea cucumbers, which can fetch high prices in Japan and South Korea.

Angry fishermen surrounded the Charles Darwin research station on Santa Cruz last February, threatened to kill Lonesome George—the last surviving member of the Pinta Island species of the Galapagos giant tortoise.

The situation got improved after the Ecuador government made concessions (让步) by increasing fishing quotas (配额), which angered conservationists. “It is tragic, the short-term gain of a few fishermen versus the long-term survival of the Galapagos,” said John McCosker of the California Academy of Sciences. “They are killing the golden goose.”

Then, the Ecuador government appointed Fausto Cepeda as the national park's new director, a post that has become a political football for the mainland government. There have been nine directors in the past 18 months.

This appointment was particularly controversial, however. Cepeda was known to have close ties with the fishing industry, and the rangers (管理员),who run the national park and reserve, rebelled.

More than 300 staged a sit-in at the park’s headquarters and prevented Cepeda from taking up his post. A battle broke out, and at least two people suffered serious injuries. Eventually, Cepeda—with the fishermen’s help- entered the park. “I am in office, i am in control. And I am trying to lower the tension,” he announced.

The Ecuador government took no chances, and sent a patrol boat to maintain the peace. A few days later, Ecuador Environment Minister Fabian Valdivicso met representatives of rangers. After discussions, he told newspapers that he had decided to remove Cepeda from the post.

However, as the population continues to rise, the long-term pressures on the islands are serious and will not disappear that easily.

“We have to balance its special environment with the needs of local people. In that sense, it is a microcosm (缩影) for all the other threatened parts of the world. So getting it right here is going to be a very, very important trick to pull off,” said Stjepic.

小题1:What does the underlined word “this” in Paragraph 5 refer to?

A.The island’s swelling population.

B.The law to limit waves of immigrants.

C.A life in paradise.

D.The tourists’ visiting the islands every year.小题2:How significant were the islands for Charles Darwin?

A.He based his theory on his studies there.

B.He built the Charles Darwin research center there.

C.He advocated the balance between ecology and people there.

D.He found the last surviving giant tortoise there.小题3:What is the primary contributing factor to the conflict between conservationists and fishermen?

A.The dismissal of the previous director of the Galapagos National Park.

B.The exploitation of the islands.

C.The government's support of Galapagos Conservation Trust.

D.Cepeda’s close tie with the fishing industry.小题4:We can learn from the passage that _______.

A.the projects of Galapagos Conservation Trust on the islands are profitable

B.conservationists get angry when fishermen are killing a goose

C.politicians from the mainland government play football on the islands

D.the government is trying to ease the tension小题5:In Paragraph 13, what does the author mean by “The Ecuador government took no chances”?

A.The government did not seize opportunities.

B.The government made no compromises.

C.The government did not run risks.

D.The government shrank from responsibilities.

题型:选择题

Angle Ⅱ类错的咬合接触关系为()

A.上颌第一恒磨牙近中颊尖咬合于下颌第一恒磨牙的颊沟

B.上颌第一恒磨牙近中颊尖咬合于下颌第一恒磨牙的颊沟远中

C.上颌第一恒磨牙近中颊尖咬合于下颌第一恒磨牙的颊沟近中

D.上颌第一恒磨牙近中舌尖咬合于下颌第一恒磨牙的近中窝上

E.上颌第一恒磨牙近中舌尖咬合于下颌第一恒磨牙的远中窝上

题型:选择题

下列哪项是慢性肺源性心脏病所不具备的

A.慢性阻塞性肺疾病

B.肺动脉高压

C.肺动脉主干栓塞

D.右心室心肌肥大

题型:选择题

以下联合体可能被视为网络的有()。

A.如果一个联合体旨在通过合作在各实体之间共享收益或分担成本,应被视为网络

B.如果一个联合体旨在通过合作在各实体之间共享统一的质量控制政策和程序,应被视为网络

C.如果一个实体与其他实体以联合方式应邀提供专业服务,应被视为网络

D.如果一个联合体旨在通过合作,在各实体之间共享同一经营战略,应被视为网络

更多题库