由于电火花加工的极性效应,当采用宽脉冲加工时,工件应接(),这种加工一般用于对零件的

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问题:

由于电火花加工的极性效应,当采用宽脉冲加工时,工件应接(),这种加工一般用于对零件的()。

考点:机械工程模具制造工艺学模具制造工艺学题库
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In my children’s lifetimes, I believe gorillas, chimpanzees and orangutans will all become extinct in the wild. So the question we have to ask ourselves is this: do we want our children to see only in zoos what used to exist in the real world (46) It is the great apes that will disappear first, because there are so few of them left, and because they’re so vulnerable to changes in their habitats.

Many of the threats to these animals result from a global economy not local pressures. The threat to the orangutan in Indonesia, for example, is largely a result of deforestation and the risks to primates in Africa result from the timber-trade and the demand for bush-meat. (47) The two work together: logging opens up the forest, which means that the bush-meat can be got out fast, to Kinshasa or to London.

(48) If we want to avoid the disaster scenario, people in developed countries will have to take a global perspective and accept responsibility for the damage export crops such as timber, coffee, cut flowers or even green beans, do to the environment. The challenge is to avoid simply imposing western attitudes on local peoples.

Already there are no truly wild places left in the world. (49) Looking at wildlife has become the preserve of the middle classes over the last twenty-odd years, and as wild animals become even rarer, so more tourists want to see them. But tour ism alone plainly cannot conserve the world’s animals; economic development is the priority.

For the future, I suspect that ff you really want to do something about wild life conservation, you would be better off putting your money into women’s education rather than just into the protection of flagship species. (50) Women often bear the direct costs of wildlife conflict; their knowledge of how to deal with conflict and how to control their own reproductive destinies may yet determine the survival of many threatened species.

Women often bear the direct costs of wildlife conflict; their knowledge of how to deal with conflict and how to control their own reproductive destinies may yet determine the survival of many threatened species.

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男,47岁。扩张型心肌病患者从事每天日常活动即出现心悸、气短症状,休息后即缓解。其心功能分级应为()。

A.心功能Ⅰ级

B.心功能Ⅱ级

C.心功能Ⅲ级

D.心功能Ⅳ级

E.心功能Ⅴ级

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患者来院急诊时,对于腹痛必须考虑的问题中哪项除外()。

A.患者所指的腹痛部位有局限性压痛时,基本上是该部位的内脏疾患

B.虽然让患者做充分的深呼吸,但腹部却丝毫不随呼吸而起伏运动时,多是弥漫性腹膜炎

C.急性胰腺炎时腹肌紧张可不明显,至少不足腹肌板样强直

D.让患者咳嗽而感觉上腹部疼痛时,均可认为是上腹部的炎症性病变

E.急性阑尾炎的早期症状中可诉中上腹或剑突下疼痛

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微生物有何特点?环境中微生物包括哪些主要类别?

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咽部深红,肿痛明显者的原因多为()

A.肺胃热毒壅盛

B.肾阴不足,虚火上炎

C.阴虚火浮

D.痰湿凝聚

E.气阴两虚,虚火上浮

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