[解析]
(1)C.细节理解题.根据第一段Gradually it came to be realized that scurvy was caused by some lack in the sailors' diet(渐渐地,人们逐渐认识到坏血病是由于水手的饮食不足引起的)以及established the fact that scurvy could be prevented by the supply of fresh fruit for the sailors(证实了向水手供应新鲜水果可以预防坏血病的事实)可知,坏死病是由于缺乏基本的物质引起的.故选C.
(2)D.推理判断题.根据最后一段The vitamins necessary for a healthy body are normally supplied by a good mixed diet,including a variety of fruit and green vegetables(健康身体所需的维生素通常由良好的混合饮食提供,包括各种水果和绿色蔬菜)以及结合前面的水手患坏死病的事例可知,保持一个好的饮食习惯是基本的要求,结合选项可知,D项to develop a good dietary habit(养成一个好的饮食习惯)符合文意.故选D.
(3)B.推理判断题.根据第二段 Nowadays it is understood that a diet which contains nothing harmful may yet result in serious disease if certain important elements are missing(现在人们知道,如果缺少某些重要元素,不含任何有害物质的饮食也可能会导致严重的疾病)可知,如果我们的饮食不全面,我们所吃的营养物质也是不完全健康的.故选B.
(4)C.主旨大意题.根据本文内容的描述以及第二段Different diseases are associated with shortages 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 (敏感度) to colds and influenza(不同的疾病都与特定维生素的缺乏有关,即使是轻微缺乏维生素C,例如新鲜水果和蔬菜中含量最丰富的维生素C,也被认为会显著增加我们对感冒和流感的易感性)可知,维生素在我们的健康中起着至关重要的作用,所以C项Vitamins play a vitally important role in people's health作为文章的主旨大意比较准确.故选C.