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我国河口海岸面临的主要挑战：一是入海泥沙急剧减少，如近几年黄河由于来水减少和断流，河口来沙仅及50年代的1/60，导致黄河三角洲遭受海水侵蚀；二是入海污染物显著增加，全国河流长度的70.6%受到污染，农田化肥施用量近20年增加4倍多，大量工业与城市污水排放，造成近海水质恶化，赤潮频发，每年仅此一项所造成的损失就以数10亿元计。 下列属于我国河口海岸面临的主要挑战的一项是( )。
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华勒斯认为，直觉总是出现在意识的边缘而不是中心。他认为应该花力气去捕捉直觉，密切注意出现在思想的支流和回浪中而不是主流中的价值的设想。据说，有些人在直觉出现以前有某种预感。他们感到某种直觉性质的东西即将出现，但并不能确切地知道究竟是什么。华勒斯称其为“暗示”，这种现象似乎并不普遍。情感上的敏感性或许是科学家应该具有的一种可贵品质。一个伟大的科学家应被看作是一个创造性的艺术家，把他看成是一个仅仅按照逻辑规则和实验规章办事的人是非常错误的。 文中画线句子的意思是( )。
An orator, whose purpose is to persuade men, must speak the things they wish to hear, an orator, whose purpose is to move men, must also avoid disturbing the emotional effect by any obtrusion of intellectual antagonism, but an author, whose purpose is to instruct men, who appeals to the intellect, must be careless of their opinions and think only of truth. It will often be a question when a man is or is not wise in advancing an unpalatable opinion, or in preaching heresies. But it can never be a question that a man should be silent if unprepared to speak the truth as be conceives it. Deference to popular opinion is one great source of bad writing and is all the more disastrous because the deference is paid to some purely hypothetical requirement. When a man fails to see the truth of certain generally accepted views, there is no law compelling him to provoke animosity by announcing his dissent. He may be excused if he shrink from the lurid glory of martyrdom. He may be justified in not placing himself in a position of singularity. He may even be commended for not helping to perplex mankind with doubts which he feels to be founded on limited and possibly erroneous investigation. But if allegiance to truth lays no stern command upon him to speak out his immature dissent, it does lay a stern command not to speak out hypocritical assent. There are many justifications of silence, there can be none of insincerity. Among the justifications for silence, the author does not include ______.
Prices determine how resources are to be used. They are also the means by which products and services that are in limited supply are rationed among buyers. The price system of the United States is a very complex network composed of the prices of all the products bought and sold in the economy as well as those of a myriad of services, including labor, professional, transportation, and public-utility services. The interrelationships of all these prices make up the "system" of prices. The price of any particular product or service is linked to a broad, complicated system of prices in which everything seems to depend more or less upon everything else. If one were to ask a group of randomly selected individuals to define "price", many would reply that price is an amount of money paid by the buyer to the seller of a product or service or, in other words, that price is the money value of a product or service as agreed upon in a market transaction. This definition is, of course, valid as far as it goes. For a complete understanding of a price in any particular transaction, much more than the amount of money involved must be known. Both the buyer and the seller should be familiar with not only the money amount, but with the amount and quality of the product or service to be exchanged, the time and place at which the exchange will take place and payment will be made, the form of money to be used, the credit terms and discounts that apply to the transaction, guarantees on the product or service, delivery terms, return privileges, and other factors. In other words, both buyer and seller should be fully aware of all the factors that comprise the total "package" being exchanged for the. asked-for amount of money in order that they may evaluate a given price. The paragraph following the passage most likely discusses ______.
An orator, whose purpose is to persuade men, must speak the things they wish to hear, an orator, whose purpose is to move men, must also avoid disturbing the emotional effect by any obtrusion of intellectual antagonism, but an author, whose purpose is to instruct men, who appeals to the intellect, must be careless of their opinions and think only of truth. It will often be a question when a man is or is not wise in advancing an unpalatable opinion, or in preaching heresies. But it can never be a question that a man should be silent if unprepared to speak the truth as be conceives it. Deference to popular opinion is one great source of bad writing and is all the more disastrous because the deference is paid to some purely hypothetical requirement. When a man fails to see the truth of certain generally accepted views, there is no law compelling him to provoke animosity by announcing his dissent. He may be excused if he shrink from the lurid glory of martyrdom. He may be justified in not placing himself in a position of singularity. He may even be commended for not helping to perplex mankind with doubts which he feels to be founded on limited and possibly erroneous investigation. But if allegiance to truth lays no stern command upon him to speak out his immature dissent, it does lay a stern command not to speak out hypocritical assent. There are many justifications of silence, there can be none of insincerity. To persuade people, it is wise to ______.
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