问题 单项选择题

It sounds like a science fiction, but researchers say it’s a scientific fact: Microscopic organisms dubbed "killer algae" are paralyzing fish with unknown toxins and then eating away at their flesh. They might be making people sick, too.
The name given to this single-cell organism, or dinoflagellate, is Pfiesteria piscimorte- literally, "fish killer. " It was discovered at North Carolina State University in 1988, but at the same time, few scientists believed in its existence, much less in its highly unusual predatory nature. But ongoing research has led to international acknowledgment of the phenomenon and, recently, research funding.
Seemingly prompted by an unknown substance secreted by fish, the aggressive creature swims into action. It sends neurotoxins into the water and air, paralyzing a fish’s nervous system, and causing it to gasp for air at the surface. Eventually the fish suffocates. The killer dinoflagellate then attaches itself to the fish and begins sucking away at its flesh. This macabre scenario may help solve several sea mysteries, such as why fishermen report seeing "fish walks" (fish trying to leave the water) and pools of dead fish with holes eaten through them.
Whether humans are affected by the dinoflagellate’s toxin remains to be seen. Researchers think it’s unlikely eating fresh fish are in danger, but anyone with frequent exposure to the creature could be in peril. Several researchers working with the algae have reported bouts of memory loss and disorientation.
To understand the killer algae further, scientists must fully characterize their toxin and determine what stimulates them to attack. They also need to know if the algae are hurting fish populations, and whether pollutants make them more likely to attack.

Which of the following statements is true

A. Scientists have solved the mystery about the fish killer.
B. More studies need to be made about the fish killer.
C. It is proved that the algae are reducing fish populations.
D. Humans have already been affected by the toxin.

答案

参考答案:B

解析: 推断题型
见第五段:To understand the killer algae further, scientists must fully characterize their toxin and determine what stimulates them to attack. They also need to know if the algae are hurting fish populations, and whether pollutants make them more likely to attack. 见下划线部分,因此可知还有更多的研究要做,因此B为答案。

问答题 案例分析题

阅读下列材料,回答问题。

材料一发端于唐宋之际的海洋发展路向,表明我国传统社会的运行轨迹开始出现了由“头枕三河、面向草原”到“头枕东南、面向海洋”的历史性转折,到宋代出现了“诸蕃惟市舶仅通”的局面,海上对外贸易极其繁盛。东起日本、朝鲜,西到地中海和非洲东部沿岸,欧洲、非洲、亚洲50多个国家与中国有贸易往来.宋代中国是亚洲一支最活跃的力量,以中国为中心,与欧洲和非洲连接在一起的亚洲多边贸易网络初具规模,指南针在地中海投入使用,大大促进了地中海交通和对外贸易的繁荣。

材料二据《明实录》载,明太祖朱元璋对中书省说:“其朝贡无论疏数,厚往而薄来可也。”又说:“朕以海道,可通外邦,故尝禁其往来。”明成祖说:“商税者,国家抑逐末之民,岂以为利。今夷人慕义远来,乃侵其利,所得几何,而亏辱大体多矣。”自成化十二年(1476年)正月起至次年三月止,赏赐贡使等项苎丝37558匹,而全国司库每年额造仅25741匹。据《皇明世法录》载,明政府下令:“凡将马牛、军需……私出外境货卖及下海者,杖一百……物货船车并入官……若将人口、军器出境及下海者,绞”,后又下令:“片板不许入海……”。

材料三中国在西方文艺复兴时期的大部分时间里,其本身就是一个世界,一个尽可能不与外界往来的世界,然而,尽管除知识名流外,其他中国人对外部世界不感兴趣,但外部世界却对中国兴趣甚浓。哥伦布航行的目标就是契丹,麦哲伦旅行的主要结果是马尼拉这块殖民地的建立,而到中国传教则成为耶稣会士的荣耀……作为一个有名无实的闭关国家,有着甚至更为封闭的儒家思想的明代中国,正在丧失它的自主性.开始依附于一个非它所创造的世界体系。

(1)依据材料一和所学知识,指出唐宋之际我国外贸路径变化的主要原因及其世界意义。

(2)依据材料二和所学知识,指出影响明朝海外贸易的主要因素。

(3)依据材料二、三并结合当时的世界形势,评述明朝的对外贸易政策。

名词解释