【答案解析】许多年前，科学家们就已经知道人们需要维生素D。维生素D帮助身体吸收钙质，从而促进骨骼和牙齿的生长并使其坚固。研究显示，缺乏维生素D会增大骨折的危险，而加量服用维生素D有助于防止骨折。健康专家们一直相信，每天短时间的日光照射能给人体提供足够的维生素D，因为人们的皮肤能把阳光转换成维生素D，并在身体里储存起来。 [解析]
For many years, scientists have known that people need Vitamin D. Vitamin D helps the body use calcium to develop and strengthen bones and teeth. Studies show that lack of the vitamin is linked to an increased risk of broken bones. Extra Vitamin D may help prevent such breaks. Health experts have traditionally believed that short periods of sunlight each day could provide enough Vitamin D. This is because human skin changes sunlight into Vitamin
D. The body then can store this substance.

【答案解析】在世界上，每年都会有约16万名15岁以下儿童被发现患有癌症。研究者发现这些病例中有84%发生在发展中国家。他们说在这些国家里只有10%的患癌症儿童能够存活。如果这些国家拥有必要的资源来发现和治疗癌症，更多的儿童能被救活。在英国和美国这样的工业国家里，患癌症儿童的存活机会就大得多。 [解析]
Around the world, about one-hundred-sixty thousand children under age fifteen are found each year to have cancer. The researchers say eighty-four percent of these cases are found in developing countries. They say only ten percent of children with cancer in these countries survive and many more could be saved if their countries had the resources needed to find cancers and treat them. Children from industrial countries like Britain and the United States who develop cancer have a much better chance to survive.