part 4

30 Milk is the best food there is for babies. It is good for children and for older people too. It has in it fat, which gives energy, and it has the most important of the materials needed for building up our bodies. Milk makes strong bones and strong teeth too. It is good for a child to drink two or three glasses of it every day. In addition, milk has in it most of the vitamins which are needed to keep us healthy. Vitamins are a discovery of the twentieth century. Two hundred years ago no one knew anything about them.

牛奶是婴儿最好的食物。 它对儿童和老年人都有好处。 它含有脂肪，可以提供能量，它还含有我们身体所需的最重要的物质。 牛奶也能强健骨骼和牙齿。 孩子每天喝两到三杯咖啡是有益的。 此外，牛奶中含有保持我们健康所需的大部分维生素。 维生素是二十世纪的发现。 两百年前，没有人知道它们的存在。

31 The vitamins are named by letters of the alphabet. Vitamin A is needed by the eyes. There is Vitamin A in milk, butter and green vegetables. It can be stored by the body. Vitamin B cannot be stored. It must be supplied all the time by some of the food we eat. The skins of grain of all sorts have Vitamin B in them.

维生素是按字母表中的字母命名的。 眼睛需要维生素A。 牛奶、黄油和绿色蔬菜中都含有维生素A。 它可以被人体储存。 维生素B不能储存。 它必须一直由我们吃的一些食物提供。 各种谷物的皮都含有维生素B。

32 Vitamin C is very important to the body. Without it our teeth become loose and our arms and legs weak. Lemons, oranges and tomatoes have Vitamin C in them. Vitamin D is the sun vitamin. We get it in milk and eggs and from sunlight on our skin. There are other vitamins, but these, A, B, C and D, are the most important.

维生素C对身体很重要。 没有它，我们的牙齿就会松动，我们的胳膊和腿也会虚弱。 柠檬、橙子和西红柿都含有维生素C。 维生素D是太阳维生素。 我们从牛奶和鸡蛋中获得维生素d，也从皮肤上的阳光中获得。 还有其他维生素，但A、B、C和D是最重要的。

33 Every person must have air and water and food to keep alive and must have these vitamins to keep well. How do we know this? How do we know what food keeps us well and healthy? We know from the effects on us and on animals of going without one sort of food or another. That is how we see which foods give us energy, which make us fat and which make us able to keep healthy. Scientists are putting together more and more knowledge about the sorts and amounts of food that our bodies need. Too little food or too much of the wrong food is bad for a person. The right amount of the food will keep a person feeling well and strong. Some people need a little more or a little less of one or another sort of food than others.

每个人都必须有空气、水和食物来维持生命，必须有这些维生素来保持健康。 我们怎么知道的？我们怎么知道什么食物能让我们保持健康呢？ 我们知道，没有这种或那种食物对我们和动物的影响。 这就是我们如何看到哪些食物给我们能量，哪些使我们发胖，哪些使我们能够保持健康。 科学家们正在收集越来越多的关于我们身体所需食物种类和数量的知识。 食物太少或吃太多不合适的食物对人都是有害的。 适量的食物会让人感觉健康和强壮。 有些人对某种食物的需求比其他人多一点或少一点。

34 Where do we get our food? We get much of it from the earth. We use some sorts of animals and birds to give us food. Great parts of the earth are covered with grass, a plant which grows with narrow green leaves and puts down roots quickly. There are more than three thousand different sorts of grasses growing. Grass has very small seeds which are used as food by birds and small animals. We have discovered how to grow grasses with larger seeds. Wheat, rice, corn, and other grains come from grass. The grain lands of the world have been planted by people. From grain we get an important part of the food that gives us energy.

我们从哪里得到食物？ 我们从地球上获得了很多。 我们用一些动物和鸟类给我们食物。 地球的大部分都被草覆盖着，这种植物长着狭窄的绿叶，很快就扎根了。 这里生长着三千多种不同种类的草。 草有非常小的种子，是鸟类和小动物的食物。 我们已经发现了如何种植种子更大的草。 小麦、水稻、玉米和其他谷物都来自草。 世界上的耕地都是人类耕种的。 从谷物中，我们获得了食物的重要组成部分，为我们提供能量。

35 The grasslands of the earth supply food to many different animals. From some of them we get meat and milk. From milk we make butter and cheese and other foods. From birds living on grain we get eggs and meat. Seeds planted in good earth supply grains and fruits and vegetables of many sorts. The seas and rivers supply fish and some sea plants for food.

地球上的草原为许多不同的动物提供食物。 从其中一些我们得到肉和牛奶。 我们用牛奶制作黄油、奶酪和其他食物。 我们从吃谷物的鸟身上得到蛋和肉。 种在肥沃土地上的种子提供了各种各样的谷物、水果和蔬菜。 海洋和河流提供鱼类和一些海洋植物作为食物。