环境学有关保护濒临灭绝的动物的高昂费用，提出应通过评估各种濒临灭绝的动物对人类的价值，以决定保护哪些动物。此法实际不可行，因为，预言一种动物未来的价值是不可能的。评价对人类现在做出间接但很重要贡献的动物的价值也是不可能的。从这段文字中可以推出的是()
A．保护对人类有直接价值的动物远比保护有间接价值的动物重要
B．保护没有价值的濒临灭绝的动物比保护有潜在价值的动物更重要
C．尽管保护所有濒临灭绝的动物是必须的，但在经济上却是不可行的
D．由于判断动物对人类价值高低的方法并不完善，在此基础上做出的决定也不可靠
参考答案：C
解析：题干中指出，通过评估各种濒临灭绝的动物对人类的价值以决定保护哪些动物的方法不可行，其隐藏的含义是：所有濒临灭绝的动物都应受到同等的保护．但是，从“高昂费用”一词可以看出，保护所有濒临灭绝的动物在经济上却不可行．由此，可确认C项是正确选项．A项与B项都明显与题干所述矛盾，不应选．D项也是错误的，题干中是讲“此法实际不可行”，而不是此法不完善、不可靠．
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| In the past all letters were sent by train or ship. Now most letters are __1__ sent by train or ship, but some are sent by air. You send a letter __2__ so that your friend may receive it sooner. A letter __3__ about twelve days to go from England to India by train or by ship. A letter can get to India by air __4__ five days now, but __5__ the time may be made shorter. __6__ people were afraid to send letters by air. They thought that the plane might fall and their friends might not receive the letter. So they sent two letters: one letter by air and __7__ by train or ship. They wanted to __8__ that the letters would be received. Planes are now almost as safe __9__ trains or ships. __10__ letters are sent by air, | ||||
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