问题 解答题

317的25倍是多少?

答案

317×25=7925.

答:317的25倍是7925.

单项选择题

根据下文回答问题:

在我国960万平方公里土地上,山地占2/3,大致可分为三级台阶。第一级台阶是世界第一大高原——青藏高原。第二级台阶从黑龙江最北端开 始,一直到云贵高原南部,平均海拔近2000米,包括内蒙古高原、黄土高原、秦岭、大巴山和云贵高原。自第二级台阶以东至东南沿海为华东平原,即第三级台 阶。上一级台阶都是下一级台阶的支撑或庇护伞。青藏高原是我国整个生态的屏障,它把寒冷空气挡在这座大墙之外,使它的东面和南面即第二级台阶形成了优良的 生态条件,温暖湿润,物种丰富。而第三级台阶属平原生态系统,现代城市生活基本上都集中在这里,第二级台阶丰富的物种资源为下一级台阶的平原生态系统提供 了生存的物资。三级台阶囊括了地球大多数生态类型,将地球自赤道至极地之间的多数陆地动植物承载其中,为人类的生存繁衍提供了物种资源。 三级台阶中最关键的是青藏高原, ★ 但目前的情况却不容乐观,由于全球气候变暖,连年干旱,青藏高原上的许多湖泊湿地渐渐干涸。青海湖是中国第一大咸水湖,现在每年退水13厘米,干涸的过程 中,矿物质析出,若干年之后,过高的矿化度会杀死湖内所有生物。近些年来过度放牧也导致了草场退化,进一步破坏了涵养水源的生态条件。一旦青藏高原上的高 寒草甸消失殆尽,整个高寒草甸将会被荒漠和沙漠所取代。青藏高原是地质灾害多发地,它就像一堆5-8公里厚的碎石镶在旋转的地球表面,顶端的线速度比平地 快很多,所以它的板块碰撞和地质灾害表现得更加突出。地震、塌方、雪崩、泥石流等比平原剧烈得多,常有半面山坡倾倒而下,山坡上的树木成片成片地随之被连 根拔起。由于气候变迁和人类无序开发,青藏高原植被覆盖率大大降低,风沙危害逐年增大。全球变暖,雪线退缩,使许多5000多米的雪山岩石裸露。冰融水量 减少,许多湿地与河流干涸,缺水的居民只能搬家。 云南省号称“植物王国”,但看到的绿色与之并不相符。云南省只有西南部的森林长势良好,而中东部大部分植被很稀疏,干热河谷和干荒地区生态 更加脆弱,水土流失相当严重,在喀斯特地形区的土层很薄,很容易被侵蚀。著名的云南石林,看上去虽然壮观,但从生态的角度去看,不过是一片石漠,在云贵许 多地点,正在形成大量新石漠区。红色土壤流失后,裸露出灰色的石灰岩,就像动物被剔去了皮肉,剩下肉架一样,比沙漠更难治理。在云南德宏地区的热带雨林, 人们砍掉它改种农作物,这样做是捡了芝麻,丢了西瓜。热带雨林是地球最重要而且无法替代的生态系统,农作物能够带来的经济效益与之相比不可同日而语。这里 的湿地、湖泊也在退缩或消失,以前碧波荡漾的纳帕海现在已消失不见。经询问才知道,是无序开发把地下水系破坏了,就像在我们的盆底钻一个孔,高原湖盆的水 全部漏掉了。

下列对原文意思的理解,准确的一项是()

A.中国整个生态格局可以分为三级台阶,三级台阶之间相互依存

B.人为的无序开发,使青藏高原的雪线退缩,植被覆盖率大大降低

C.对生态系统的破坏,使得青藏高原板块碰撞和地质灾害表现得更加突出。

D.我国各地形成大量新石漠区及西南地区热带雨林遭到破坏,导致我国生态危机十分严重

单项选择题

Questions 11-15 are based on the following passage.
Davis, California, like many other American cities, has been threatened by unchecked growth, swarming automobiles, and steeply rising energy costs. But unlike towns and cities which leave energy policy to the federal government or energy corporations, the citizens of Davis have acted on their own.
After lengthy debate, Davis’ City Council moved to curb growth. It turned against the automobile and embraced the bicycle as a means of transport. It sponsored an inquiry into energy uses and endorsed a series of measures aimed at reducing energy consumption by as much as one half. It cut back the use of petroleum-derived pesticides on the thousands of trees and shrubs that shade the city’s streets, adopting instead a policy of biological control for insects. The city’s own cars and trucks have been transformed into a fleet of compact vehicles. When a Davis employee has to get around town, he borrows a bike from the city rack. Davis even passed a law formally and solemnly sanctioning the clothesline.
The citizens of Davis have been involved in progressive city planning and energy conservation since 1968, when they persuaded the City Council to facilitate bicycle transportation by developing a system of bikeways. The City’s general plan for development, drawn up in 1972, was based on questionnaires distributed to residents. When a survey of residents showed that automobiles represented 50 percent of energy consumption and space heating and cooling accounted for 25 percent, transportation and building construction became important focal points in the Davis plan.
Armed with survey information revealing that a building’s east-west orientation on the lot, as well as its insulation, window area, roof and wall colors, overhang shading, and other factors greatly influenced space heating and cooling needs, the City Council drew up a building construction code which greatly reduced the cost of winter heating and eliminates the need for air conditioning even on Davis’ hottest (114°) day. To demonstrate to local builders and developers methods for complying with the new code, Davis built two model solar homes, a single-family dwelling which takes advantage of natural southern exposure sunlight and a duplex adaptable to difficult siting situationswhere direct sunlight is blocked.Many of Davis’measures simply facilitate natural solar heating or sun-shading. Where most communities require that fences be built close to houses, Davis realized that practice meant blocking winter sunlight. New fences in Davis must be placed closer to the street, giving residents the benefit of natural solar heat in winter. Reducing required street widths provides more shade and saves asphalt to boot.
Davis’ other energy conserving moves run the gamut—from a city ordinance encouraging cottage industry (to cut down on commuting and the need for new office building construction) to planting evergreens on city streets to reduce leaf pickup in the fall, from a ban on non-solar swimming pool heaters to a recycling center that supports itself by selling $3,000 worth of recyclables a month.

It appears that Davis is______.

A.a "good old American town"

B.committed to social justice

C.a medium-to-small-size city

D.blessed by a p radical element in the population