In the early days of sea travel, seamen on long voyages lived exclusively on salted meat and biscuits. Many of them died of scurvy, a disease of the blood which causes swollen gums, livid white spots on the flesh and general exhaustion. On one occasion, in 1535, an English ship arrived in Newfoundland with its crew desperately ill. The men’s lives were saved by Iroquois Indians who gave them vegetable leaves to eat. Gradually it came to be realized that scurvy was caused by some lack in the sailors’ diet and Captain Cook, on his long voyages of discovery to Australia and New Zealand, established the fact that scurvy could be warded off by the provision of fresh fruit for the sailors.
Nowadays it is understood that a diet which contains nothing harmful may yet result in serious disease if certain important elements are missing. These elements are called “vitamins”. Quite a number of such substances are known and they are given letters to identify them, A, B, C, D, and so on. Different diseases are associated with deficiencies of particular vitamins. Even a slight lack of Vitamin C, for example, the vitamin most plentiful in fresh fruit and vegetables, is thought to increase significantly our susceptibility to colds and influenza.
The vitamins necessary for a healthy body are normally supplied by a good mixed diet, including a variety of fruit and green vegetables. It is only when people try to live on a very restricted diet, say during extended periods of religious fasting, or when trying to lose weight, that it is necessary to make special provision to supply the missing vitamins.
单选题
Scurvy is a disease that is caused by _____.
【正确答案】
C
【答案解析】文章第一段第五句提到“Gradually it came to be realized that scurvy was caused by some lack in the sailors’ diet”， 由此可知， 坏血病是由于饮食中缺少重要的物质造成的， lack对应C选项中的want。 虽然后文提到食用新鲜的水果蔬菜可以避免罹患坏血病， 但最根本的原因在于蔬菜水果中含有丰富的维生素。 因此， 正确答案为C选项。
单选题
In the last sentence of Paragraph I, “warded off” could probably be replaced by _____.
【正确答案】
C
【答案解析】根据文章首段第四句提到的“The men’s lives were saved by Iroquois Indians who gave them vegetable leaves to eat”， 由此可知， 食用新鲜水果蔬菜可以避免患上坏血病。 再根据题干关键词“warded off”后接的“by the provision of fresh fruit for the sailors”， 由此可知， 此处“warded off”应该有“避免”的意思， 与C选项相对应。 因此， 正确答案为C选项。
单选题
To avoid such disease as scurvy, it’s better for us _____.
【正确答案】
D
【答案解析】文章第一段首句就指出“In the early days of sea travel, seamen on long voyages lived exclusively on salted meat and biscuits”， 下文又提到通过摄入新鲜蔬菜水果预防坏血病的方法。 由此可知， 早期水手们只有腌肉和曲奇的食谱在加入了新鲜蔬菜以后， 坏血病患病状况得到了有效的控制。 此处， 作者在强调的其实是合理饮食习惯的重要性， 对应题目中的D选项。 因此， 正确答案为D选项。
单选题
Based on the passage we can safely conclude that if our diet is not comprehensive enough_____.
【正确答案】
B
【答案解析】通读全文可知， 作者主要意图是为了强调均衡饮食的重要性。 文章第一段首句提到“In the early days of sea travel, seamen on long voyages lived exclusively on salted meat and biscuits”， 根据常识可知， 腌肉和曲奇其实很有营养， 能够补充我们日常所需很多的热量，但是如果只吃这两种食物的话， 会增加我们患坏血病的风险。 换句话说， 如果我们的饮食不均衡， 再有营养的食物也是不健康的。 B选项表述与事实相符， 为正确答案。 A选项在文章中没有体现， 可排除。 C选项过分夸大了绿色蔬菜叶子的作用， 可排除。 而根据文章最后一段第二句提到的“during extended periods of religious fasting, or when trying to lose weight, that it is necessary to make special provision to supply the missing vitamins”， 也就是说不论是在斋戒还是减肥期间， 补充所需维他命是很有必要的。 D选项表述与事实不符， 可排除。 因此， 正确答案为B选项。
单选题
Which of the following sentences best expresses the central ideal of the passage?
【正确答案】
C
【答案解析】阅读全文， 文章以败血症为例引出维生素的重要性， 再联系文章最后一段首句提到的“The vitamins necessary for a healthy body are normally supplied by a good mixed diet, including a variety of fruit and green vegetables”， 作者此处指明了获取维他命的主要途径。 C选项表述符合题意， 为正确答案。