9．You should drink four to six glasses of each day．
10．Food that is not good for you is called food．
译文
现在你将会学习到一些能更好地照顾自己身体的方法。
牙齿对你来说是很重要的。你曾经听到过那些没有牙齿的人说话吗？他们说话很不清晰。你需要牙齿来帮你更好地讲话。没有牙齿的人也会存在另外一个问题，他们的表情不会像有牙齿的人那么漂亮可爱。
牙齿非常重要的另一个原因是它能咀嚼食物。如果没有牙齿，你只能吃软的食物，你将不能吃牛排、苹果或汉堡包。
汤姆的父亲是一名牙医，他来到教室给大家讲解保护牙齿的问题。他给每个学生一支牙刷和一小管牙膏，给大家看了一些关于正确刷牙姿势的图片。他说：“保护牙齿要从正确的饮食开始。每天应吃些干酪、绿叶蔬菜，并且喝三杯或更多的牛奶，尽量不要吃糖，多吃些水果对你是有好处的。
“你应该充分咀嚼食物。咀嚼能够锻炼咽喉、齿龈和牙齿，这些锻炼也是有益的。并且，咀嚼能帮助消化。
“记得饭后要刷牙或漱口。刷牙时应顺着牙齿生长的方向刷，上面的牙齿往下刷，下面的牙齿往上刷。用正确的方式刷牙能够帮助你将牙齿间细小的食物刷掉，而且保证你不会将食物刷进牙龈。注意！不要把你的牙齿当作工具去咬硬物或坚果，你可能会弄碎牙齿。
“你每年应该去看两次牙医，如果你的牙齿开始腐烂，你自己是看不到的，但是牙医能告诉你。即使你十分仔细地刷牙，有时也会有一些食物留在牙齿间。每天应该用牙线来清除那些刷牙后还残留的食物。”
像保护牙齿一样，你也应该保护视力。当你在阅读的时候，要确保有足够的光线，并且照射过来的光线应高过你的肩膀。
不要正视太阳。当太阳非常明亮时，比如在海边或雪地里，要戴上太阳镜。好的食物也能帮助保护你的眼睛，比如胡萝卜中的维生素能帮你在夜晚看清东西。当你使用剪刀或尖的工具时，应十分小心，让它远离你的眼睛。对周围其他人也要小心，不要伤害别人的眼睛。
你已经了解到如何保护牙齿和眼睛，现在我要告诉你如何照顾好自己的身体。
你应该深呼吸，它可以帮助你的身体更好地工作。同时，站立的时候你应该保持脑袋与肩膀挺直。如果站姿正确，你的身体内部会有足够的空间来更好地工作。
你必须吃健康的食物，还需要喝水。如果每天喝4—6杯水，你的身体将会处于最佳状态。
你也可以用水来清洗。你需要每天都洗澡，至少每周洗一次头发。如果清洗头发的次数足够，它会很有光泽。你还需要每天穿干净的衣服。
确保晚上有足够的睡眠。每天晚上，你应该有8—10个小时的睡眠。如果你的身体每天都在运动，它会感到疲倦。你需要保持强壮，睡眠可以让倦怠的身体得到休息。
你不仅要保持身体清洁，还应该努力使自己的思想干净。你认为是什么使你觉得快乐或不快乐？如果你爱你的朋友，你会善待他们。你应该友好且充满爱心，如果让自己的头脑中充满了不好的想法，你不会感到高兴。为了健康，你一定不想让垃圾食品填满肚子。同样道理，为了有一个健康快乐的心智，你需要用世上的好思想来填充头脑。你要尽自己所能，让思考、阅读、行动都是最好的。
练习
在空格处填写答案。
1．我能让我的牙齿保持健康，通过吃一些食物如 ， ，
和 。
2．为了锻炼咽喉和牙齿，我需要 咀嚼食物。
3．我刷牙时应顺着牙齿 的方向刷。
4．每年，我应该看 牙医。
5．我不应该把牙齿当成一个 。
6．在强光下，你应该戴 眼镜。
7．为了在晚上看得更清楚，你应该吃 。
8．你应该每 洗澡。
9．你每天应该喝4到6杯 。
10．那些对你不好的食物被称为 食物。？
1．cheese （奶酪），milk（牛奶），leafy vegetables（绿叶蔬菜）
2．well（充分） 3．grow（生长）
4．twice（两次） 5．tool（工具）
6．sun（太阳） 7．carrots（胡萝卜）
8．day（天） 9．water（水）
10．junk（垃圾）
09 Electricity 和电流安全相处
Scientists realize that they do not know all about electricity. They know how electricity acts， but they do not know why it acts the way it does.
One of the keys to understanding electricity is understanding lightning. When some of the electrical charges in clouds move from cloud to cloud or from a cloud to the ground， we see a huge spark. This spark we call lightning. Benjamin Franklin did a famous experiment. He attached a key to the end of a kite string. Franklin flew his kite in the air during a thunderstorm. The kite became charged with electricity. A spark jumped from the key to his finger. By this dangerous experiment Franklin proved that lightning is electricity.
Atoms， electrons， and electricity are related to each other. All objects are made up of atoms. Each atom is made of tiny particles called protons and electrons among other things.
Protons are found in the center of the atom. They stay in the center of the atom and never move out. Electrons revolve around the protons and can travel out of the atom. When electrons are removed or added to an atom， that object becomes electrically charged. When an object has more protons than electrons， the object is positively charged. The object that receives the electrons is negatively charged. When an object has an equal number of positive and negative particles， the object is neutral.
Although scientists know that lightning is a form of electricity， they do not know how to make use of it. The electricity from lightning comes and goes in a flash. In order to be useful， electricity must flow. Electricity that flows is current electricity.
An Italian scientist， by the name of Volta， made an important discovery. He found that when two different metals connected by a wire were placed in certain liquids， an electric charge would flow through the wire. The two pieces of metal were electrodes. The liquid was called an electrolyte. Volta had discovered how to make a wet cell battery.
Electricity must have a conductor. Conductors are materials that carry electricity from place to place. Most metals are good conductors， but some are better than others. Copper and aluminum wires are very good conductors. A covering on the wires， called an insulator， is necessary to keep the electricity from flowing out of the wires into the wrong place. Electricity will not flow through an insulator. Electricity is not safe and should never be used without insulation. Materials often used as insulators are rubber， glass， and cloth.
The wire which carries the electric current is called a circuit. Electricity must always travel in a complete circle. That is， it must start and end at the electric cell. A switch is used to break the circuit. A break in the circuit stops the flow of electricity. When the switch is open， the current stops； when the switch is closed， the electricity begins to flow again.
Electricity has many uses. If it is used correctly， it is helpful in doing many kinds of work. It lights our homes. It moves large trains. It helps lift heavy loads. If it is not used correctly， it can be very harmful. Some rules to remember when working with electricity are listed in the following.
Rules and Safeguards to Follow：
1. Have dry hands before touching a switch， electric cord， fuse， or any type of electrical equipment.
2. Do not allow any part of your body to touch a water pipe or faucet while working with electricity.
3. Do not stand in water or on a wet surface when working with electricity.
4. Check all cords to see that they are properly insulated.
In addition to these rules， safeguards must be taken to prevent fires when electricity has been routed into a building. One way that is used to prevent fires is to route the circuit through a fuse. A fuse is a small insulated container through which a thin piece of metal is stretched. If too much current passes through the strip， the metal will burn and break the circuit. A circuit breaker also prevents electrical wires from carrying too much current. The circuit breaker does the same job as a fuse but does not have to be replaced. The breaker switch can be returned to its closed position in order to restore the current.