The American believe that anybody can become President of the United States. In a recent Hollyhood comedy(喜剧), that is exactly what happens.

    Dave Kovic, played by Kevin Kline, is a kind-hearted man who runs a business that finds people jobs. He leads a typical(典型的) American way of life, except for one thing— he looks exactly like the President, Bill Mitchell. In fact, the only thing that makes him different from the nation's leader is that he is very nice!

    The president has started using look-alikes during some public appearance. Dave is offered a chance to “serve his country” by becoming one. However, things go wrong. The President becomes very ill and Dave ends up acting as the President forever.

    Director Ivan Reitman, who made the popular and successful comedies like Twins, Ghostbusters and Legal Eagles, could have gone for easy laughs by making fun of the American government. Instead, Dave is an attractive comedy about an ordinary man in extraordinary situations. Kevin Kline gives a double performance as Dave and the President, and Sigourney Weaver is at her best as his First Lady. The love story that develops between her role and Dave is a real classic(经典).

    The film is 100% American. However, if you've ever felt that anybody could do a better job running the country than the people in power, then you'll enjoy Dave!

----_       do you eat fast food?

                          ---- Twice a week.

生物柴油是一种可再生的清洁能源，其应用在一定程度上能够减缓人类对化石燃料的消耗．科学家发现，在微生物M产生的脂肪酶作用下，植物油与甲醇反应能够合成生物柴油（如图）

（1）用于生产物柴油的植物没不易挥发，宜选用____、____方法从油料作物中提取．

（2）筛选产脂酶的微生物M时，选择培养基中添加的植物油为微生物生长提供____ ，培养基灭菌采用的最适方法是____ 法．

（3）测定培养液中微生物数量，可选用____ 法直接计数；从微生物M分离提取的脂肪酶通常需要检测____，以确定其应用价值；为降低生物柴油生产成本，可利用____ 技术使脂肪能够重复使用．

（4）若需克隆脂肪酶基因，可应用耐热DNA聚合酶催化的____ 技术．

阅读下文，完成后面题目。
愚公移山
      太行,王屋二山，方七百里，高万仞。本在冀州之南，河阳之北。
     北山愚公者，年且九十，面山而居。惩山北之塞，出入之迂也。聚室而谋曰：“吾与汝毕力平险，指通豫南，达于汉阴，可乎？”杂然相许。其妻献疑曰：“以君之力，曾不能损魁父之丘，如太行、王屋何？且焉置土石？”杂曰：“投诸渤海之尾，隐土之北。”遂率子孙荷担者三夫，叩石垦壤，箕畚运于渤海之尾。邻人京城氏之孀妻有遗男，始龀，跳往助之。寒暑易节，始一反焉。
      河曲智叟笑而止之曰：“甚矣，汝之不惠！以残年余力，曾不能毁山之一毛，其如土石何？”北山愚公长息曰：“汝心之固，固不可彻，曾不若孀妻弱子。虽我之死，有子存焉；子又生孙，孙又生子；子又有子，子又有孙；子子孙孙无穷匮也，而山不加增，何苦而不平？”河曲智叟亡以应。
      操蛇之神闻之，惧其不已也，告之于帝。帝感其诚，命夸娥氏二子负二山，一厝朔东，一厝雍南。自此，冀之南，汉之阴，无陇断焉。