根据我们飞凡学员的一线考试反馈，SWT小作文近期出现了一些机经里没有涵盖的新题目。

既然有新题出现，飞凡必然冲在一线为大家扫除备考障碍！这一期文章我们邀请到了悉尼校区写作老师Summer，为大家在网上扒出了考试原文（高度疑似），赶紧跟着Summer老师一起来消化一下吧~

完整文本

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Vitamin D refers to a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, iron, magnesium, phosphate, and zinc. In humans, the most important compounds in this group are vitamin D3 (also known as cholecalciferol) and vitamin D2 (ergocalciferol). Cholecalciferol and ergocalciferol can be ingested from the diet and from supplements. Very few foods contain vitamin D; synthesis of vitamin D (specifically cholecalciferol) in the skin is the major natural source of the vitamin. Dermal synthesis of vitamin D from cholesterol is dependent on sun exposure (specifically UVB radiation).

Vitamin D from the diet or dermal synthesis from sunlight is biologically inactive; activation requires enzymatic conversion (hydroxylation) in the liver and kidney. Evidence indicates the synthesis of vitamin D from sun exposure is regulated by a negative feedback loop that prevents toxicity, but because of uncertainty about the cancer risk from sunlight, no recommendations are issued by the Institute of Medicine (US) for the amount of sun exposure required to reach vitamin D requirements. Accordingly, the Dietary Reference Intake for vitamin D assumes no synthesis occurs and all of a person's vitamin D is from food intake. As vitamin D is synthesized in adequate amounts by most mammals exposed to sunlight, it is not strictly a vitamin, and may be considered a hormone as its synthesis and activity occur in different locations. Vitamin D has a significant role in calcium homeostasis and metabolism. Its discovery was due to effort to find the dietary substance lacking in rickets (the childhood form of osteomalacia).

参考答案

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Vitamin D refers to a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, iron, magnesium, phosphate, and zinc, and dermal synthesis of vitamin D from cholesterol is dependent on sun exposure, and it is not strictly a vitamin, and may be considered a hormone as its synthesis and activity occur in different locations, and very few foods contain vitamin D, and it was discovered in finding the dietary substance lacking in rickets.（灰色部分可不答） –63/75

当然大家也不要一看到“新题目”就被吓住了，就目前来看，新题目的命中率还相对较低。大家还是要好好准备机经里的已知老题喔~