关于物体所受外力的合力做功与物体动能的变化的关系有以下四种说法：①合力做正功，物

下列各句中，加点的成语使用恰当的一组是                    （   ）

A．收入差别过大造成不少骨干教师流失，对那些普通学校而言，无异于釜底抽薪。

B．这部影片的故事情节和演员的表演都很难让人满意，但瑕不掩瑜，它的音乐还是让人称道的。

C．为了培植健康的金融市场，近几个月来，国家有关部门开始联手，严厉打击在金融市场上翻云覆雨的“资金贩子”。

D．在“校园文化艺术节”开幕式上，李校长抛砖引玉的即兴发言，博得了全场一片掌声。

财务分析的主要内容包括（）。

A.偿债能力评价、营运能力评价、盈利能力评价、财务状况综合评价

B.偿债能力评价、经营风险评价、营运能力评价、盈利能力评价

C.偿债能力评价、营运能力评价、资产结构评价、财务状况综合评价

D.资产结构评价、经营风险评价、盈利能力评价、财务状况综合评价

Every day of our lives we are in danger of instant death from small high-speed missiles from space—the lumps of rocky or metallic debris which continuously bombard the Earth. The chances of anyone actually being hit, however, are very low, although there are recorded instances of "stones from the sky" hurting people, and numerous accounts of damage to buildings and other objects. At night this extraterrestrial material can be seen as "fireballs" or "shooting stars", burning their way through our atmosphere. Most, on reaching our atmosphere, become completely vaporised.

The height above ground at which these objects become sufficiently heated to be visible is estimated to be about 60-100 miles. Meteorites that have fallen on buildings have sometimes ended their long lonely space voyage incongruously under beds, inside flower pots or even, in the case of one that landed on a hotel in North Wales, within a chamber pot. Before the era of space exploration it was confidently predicted that neither men nor space vehicles would survive for long outside the protective blanket of the Earth’s atmosphere. It was, thought that once in space they would be seriously damaged as a result of the incessant downpour of meteorites falling towards our planet at the rate of many millions every day. Even the first satellites showed that the danger from meteorites had been greatly overestimated by the pessimists, but although it has not happened yet, it is certain that one day a spacecraft will be badly damaged by a meteorite.

The greatest single potential danger to life on Earth undoubtedly comes from outside our planet. Collision with another astronomical body of any size or with a "black hole" could completely destroy the Earth almost instantly.

Near misses of bodies larger than or comparable in size to our own planet could be equally disastrous to mankind as they might still result in total or partial disruption. If the velocity of impact were high, collision with even quite small extraterrestrial bodies might cause catastrophic damage to the Earth’s atmosphere, oceans and outer crust and thus produce results inimical to life as we know it. The probability of collision with a large astronomical body from outside our Solar System is extremely low, possibly less than once in the lifetime of an average star. We know, however, that our galaxy contains great interstellar dust clouds and some astronomers have suggested that there might also be immense streams of meteorite matter in space that the Solar system may occasionally encounter. Even if we disregard this possibility, our own Solar system itself contains a great number of small astronomical bodies, such as the minor planets or asteroids and the comets, some with eccentric orbits that occasionally bring them close to the Earth’s path.

What is the greatest danger to life on Earth？（）

A．Collision with small high-speed missiles.

B．Collision with an astronomical body.

C．Collision with stones from the sky.

D．Collision with spacecrafts.

治疗重度妊娠高血压综合征首选的药物是

A．氯丙嗪

B．20%甘露醇

C．白蛋白

D．双氢克尿塞

E．硫酸镁

2010年两会期间，一些人大代表通过调研，建议外向型企业在面临国际市场萎缩的形势下，应该进一步练好“内”功，增强竞争力。这里的练好“内”功主要是指企业要（）

A.努力将外销产品转内销

B.努力开拓产品销售的国内市场

C.尽快使自己的产品升级换代

D.通过自主创新形成竞争优势