A rainforest is an area____(cover) by tall trees with the total high rainfall spreading quite equally through the year. Rainforests have a great effect on the world environment because they can take in heat from the sun and adjust the climate.____the forest cover, these areas would reflect more heat into the atmosphere,____ (warm) the rest of the world. Losing the rainforests may also influence wind and rainfall patterns, potentially causing certain natural disasters all over the world.

    In the past hundred years, humans ____(begin) destroying rainforests in search of three major resources: land for crops, wood for paper and other products, land for raising farm ____ (animal). This action affects the environment as a whole. For example, a lot of carbon dioxide in the air comes from burning the rainforests. People____(obvious) have a need for the resources we gain from cutting trees,____ we will suffer much more than we will benefit.

    Rainforests are often called the world's drug store. More than 25% of the medicines we use today come from plants in rainforests. However, fewer than 1% of rainforest plants have been examined for their ____(medicine) value. It is extremely likely ____our best chance to cure diseases ____(lie) somewhere in the world's shrinking rainforests.

阅读下列材料：

材料一

战国时期自由买卖的土地私有制已经确立，大量农民因土地兼并失去本业或不胜地主商人的剥削，自愿放弃本业，转向工商业求生计，所谓“从贫求富，农不如工，工不如商”；所谓“田之利十倍，珠玉（经商）之利百倍”……周国人风俗，不爱做官吏，专心做工商……鲁国人喜欢讲儒学，后来风俗改变，经商谋利比周人更迫切，……到战国末年，大商人（指吕不韦）终于参加了秦国的政权。

材料二

战国时期富商大贾……成为社会上最活跃的一种人。孟子主张对工商业什一而税，去关市之征。他的主张没有一个国君采用……大商贾所使用的人，一种是伙计，如洛阳贫民到富商家学商业，替富商贸易，走遍天下各都市。更多的一种是大商贾凭借财势，用高利贷．掳掠等方式，压迫穷人做奴隶，从事商业．农业．手工业劳动……吕不韦为秦相国时，封河南洛阳十万户……并不满足于十万户的封建性地租，他占有奴隶一万人，驱使他们从事各种劳动，垄断洛阳的工商业。

——以上材料均引自范文澜《中国通史简编》

请回答：

美国1787年宪法规定：任何一州都不得“缔结任何条约，参加任何同盟或邦联”；未经国会同意，“不得对进出口货物征收任何进口税或关税”；“未经国会同意，不得在和平时期保持军队或战舰。不得与他州或外国缔结协定或盟约。”这些规定体现的原则是（         ）

下列命题中，正确的是（　　）