(m-3)(m+4)=______.

题型:填空题

问题:

(m-3)(m+4)=______.

考点:多项式
题型:填空题

2005年7月7日,中国国家 * * 胡 * * 出席八国集团同中国、印度、巴西、南非、墨西哥领导对话会,主要围绕的问题是

A.全球经济发展

B.落实千年发展目标

C.深化南北对话

D.应对气候变化

题型:填空题

灵敏度是描述传感器的输出量(一般为非电学量)对输入量(一般为电学量)敏感程度的特性参数。

题型:填空题

Few creatures on earth are as cute as the black lion tamarin, and few have as dramatic a story line. Pug-nosed and diminutive, with a comic fringe of hair, these monkeys dwell in trees in small tracts of forest in southeastern Brazil. Or they did until 1905, when they were declared extinct. No one saw a black lion tamarin again in the wild until 1970. Later, in the 1990s, some Brazilian researchers turned up a small set of isolated, inbred populations scattered over a wide region. Since that time, they have been engineering tamarin migration, doing everything they can to save the world’s most distinctive primates.
Although they are no larger than house cats, tamarins have brains big for their size and a family life organized like our own. They live in groups anchored by an adult male andadult female, along with their offspring. When a mother bears young, she usually produces twins, and although members of the group share in their upbringing, it is most often the father who carries them around in the trees, where the families feed on fruits, insects and bird’s eggs.
Unhappily for the lion tamarins, their tree-bound niche began to disappear after the Portuguese landed in Brazil and began clearing forest to make room for Rio de Janeiro, the settlements and farms. As is the case for so many threatened species, the breakup of their habitat sounded the death knell for tamarins, depriving them of the continuity of forest they require to remain abundant and safe from potential threats in any single vicinity. The animals avoid predators by hardly ever coming down from the trees, so even a narrow logging road through a forest can begin the breakup by preventing them from moving from one patch of forest to another.
A simple solution was to build bridges across roads, allowing the monkeys to move from one forest to another. With some lumber and the researchers’ work, habitats that had been separated became continuous again, improving opportunities for migrating and mating.
The next step was to broaden the distribution of the population. The researchers captured two families of black lion tamarins and moved them to a new forest. After a year, the moves were declared a success: Not only had 80 percent of the tamarins survived, but they had also produced new offspring. So far, so good. The researchers had learned the animals could adjust to the new habitats, even if the insects there tasted a little different or the trees were a slightly different size.
The techniques for saving species in the wild vary. Species with less stringent habitat requirements, like wild turkeys, have been rescued by moving them into new settings as well as outlawing their killing. More challenging to preserve are species that require a lot of land, like elephants, and species that have highly specific requirements for habitat and prey -- like black-footed ferrets. Ultimately, as in all challenges, knowledge is power to save wild species from extinction.

The advice the author missed giving in saving wild species is ______.

A.having a thorough understanding of the requirements needed

B.having enough human and financial resources

C.outlawing the killing of the protected species

D.different techniques for different animals

题型:填空题

产生咬边的原因是:焊接电流过大、运条速度不当、坡口间隙不合适、采用了短弧、角焊缝的焊条角度不当等。( )

题型:填空题

负压原油稳定装置中,原油稳定器(塔)的操作温度与稳定压力有密切的关系,在一定的操作范围内,压力越高,相应的温度()。

A.降低

B.提高

C.无变化

D.不能确定

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