Learn English with American Primary School Textbooks

Chapter 8 Social Life (8)
Electric cords should be checked before they are plugged into the wall outlet. The insulation should not be worn thin or broken. All electric cords should be in sight and not covered by rugs or heavy furniture. used. Stay away from electric poles or boxes. Never go near a fallen or hanging wire.
Vocabulary
Lightning ["laitni?] n. Lightning;

adj. lightning fast
Spark [spɑ: k] n. Sparks, Mars, the slightest;
vi. To emit sparks, to emit flashes;
vt. make big interest

kite [kait] n. kite
electron [i"lektr? n] n. electron
Proton ["pr? ut? n] n. proton
Neutral ["nju:tr? l] adj. Neutral, impartial, dim, neutral;
n. neutral person, neutral country
Electrode [i"lektr?ud] n. electrode
Electrolyte [i"lektr?ulait] n. electrolysis, electrolyte
battery ["b?t?ri] n. (accumulator) battery (group), row of guns, gun group, a set

conductor [k? n"d? kt?] n. (band) conductor, conductor, train conductor, <electricity> conductor

copper ["k? p?] n. Copper, copper coins

aluminum["?lju:"minj? m] n. 〈US〉aluminum
Insulator ["insjuleit?] n. Substance or device for insulation, heat insulation or sound insulation

Rubber ["r? b?] n. (synthetic) rubber, eraser, blackboard eraser, rubber overshoes

circuit ["s?: kit] n. circuit, line, roundabout
cord [k? : d] n. (thin) rope, corduroy pants

fuse [fju:z] vt. & vi. melting, fusion, merger;
n. fuse, fuse, fuse, fuze

faucet ["f?: sit] n. 〈America〉faucet
route [ru:t] n. road, route, distance

outlet ["autlet] n. exit, way out, way to vent, dealership

rug [r? ɡ] n. small rug
Practice
Write true or false.
1. Protons are found in the center of the atom.

2. Only protons can travel out of an atom.

3. All objects are made up of atoms.

4. When an atom has an equal number of negative and positive charges, it is neutral.

5. When an object has more protons than electrons, the object is neutral.

6. Franklin's experiment was a very dangerous one.

7. Scientists do not know all about electricity．

Match these items.
1. Ben Franklin2． circuit
3. switch4． Volta
5. insulation6． conductor
a. electricity that flows b． covering
c. circuit breakerd． copper wire
e. discovered battery f． lightning and electricity
Translation
Scientists realized that they hadn't fully understood electricity. They knew how it works, but not why.

One of the key elements to mastering electricity is understanding lightning.When the charged clouds are moving close to each other or the clouds are close to the ground, we will see huge sparks, we call these sparks lightning.Benjamin Franklin performed a famous experiment in which he attached a key to the end of a kite and released it into the air during a thunderstorm.The kite was charged, and the spark from the key in the air hit his finger.Through this dangerous experiment, Franklin proved that lightning is electricity.

Atoms, electrons and electricity are all three related.All matter is made of atoms, and each atom is made of even tinier protons and electrons.

The proton is at the center of the atom and stays the same all the time, it doesn't drift out.Electrons are swimming around the proton and are likely to escape from the atom.When electrons are transferred from one atom to another, the object is charged.Objects that get electrons are negatively charged, and when the number of positive and negative charges on an object is equal, the object exhibits electrical neutrality.

Although scientists know that lightning is electricity, they don't know how to use it.Lightning flashes, and electricity must be able to flow if it is to be used.Flowing electricity is current.

An Italian scientist named Volta made a major discovery.He found that when two different metals are connected together by a wire, and a special fluid is stored in this wire, electric charge will flow in this wire.The two pieces of metal are the electrodes, and the fluid is called the electrolyte.So Volt discovered how to make a "wet battery".

Electric current must have a conductor, and a conductor is a material that can conduct electricity.Most metals are good conductors, but some conduct electricity better than others, such as copper and aluminum.Putting a layer of insulation on the outside of the wire can prevent the current from flowing from the wire to other substances.Electric current cannot flow through the insulator, and it is very unsafe, so it is absolutely not possible to use electric current without insulation.Substances commonly used as insulating materials are rubber, glass and cloth.

Conductive metal wires are called circuits, and electricity must flow through a complete circuit.That is, the current flows from the battery and finally flows into the battery.Switches are often used to control the on-off of the circuit. If the circuit is disconnected, the current cannot flow in the circuit.When the switch is open, there is no current in the circuit, and when the switch is closed, there is current in the circuit.

Electricity has many uses, and if used properly, it can be useful for many jobs.Electricity brings light to homes, runs trains, and lifts heavy objects.It can be dangerous if not used properly.Some rules that should be remembered in live working situations are listed below.

We should abide by the following rules and safety measures:
1. Hands must be dry before touching switches, wires, fuses or any electrical appliances.

2. In the case of live work, do not let any part of your body touch the water pipe or the faucet.

3. In the case of live work, do not stand in the water or wet ground.

4. Check all wires and cables to make sure all wires are well insulated.

In addition to these rules, certain safety measures should be taken in buildings with electrical wires to prevent fires.An effective way to prevent fires is to put a fuse in the wire. A fuse is a very thin piece of metal enclosed in an insulating tube.If a high current flows through the wire, the fuse will melt, cutting off the current.A circuit breaker also prevents high currents from flowing through the wires, and it does the same job as a fuse, but it doesn't replace it.The circuit breaker switch can return to the closed state, so as to realize the continuous flow.

Inspect the cord before plugging it into an electrical outlet, the insulation may be frayed or damaged.All cords must be visible and not covered by carpet or heavy furniture.Electrical equipment should be turned off when not in use.Stay away from electrodes or electrical boxes, and away from broken or dangling wires.

Exercise
True or false.

1.The proton is at the center of the atom.

2.Only protons can escape from atoms.

3.All matter is made up of atoms.

4.An atom is electrically neutral when the number of positive and negative charges in the atom is equal.

5.When there are more protons than electrons in an object, the object is electrically neutral.

6.Franklin's experiment was very dangerous.

7.Scientists don't yet fully understand electricity.

Match the following.

1.Benjamin Franklin a.flowing electricity

2.current b.cover
3.switch c.breaker
4.Volt d.copper wire

5.Insulator e.Invent the battery

6.conductor f.lightning and electricity

True or false:

1. true 2． false 3． true
4. true 5． false 6． true
7. true
With each item:

1→f2→a3→c
4→e 5→b6→d
10Choose Snacks teaches you how to eat snacks

Snack is food eaten between main meals; it serves different functions in our daily diet. For instance, healthy nutritious snacks can help people with low dietary intake, poor appetite or who are underweight to replenish the deficiency in the main meals, and to innutrient the intakes. For healthy people, try to choose healthy snacks with appropriate portions, so that appetite for the next main meals would not be affected and additional weight gain would be minimized.
Here are some tips for choosing snacks:

1. Avoid high fat snacks
Since high fat snacks may lead to overweight easily, and snacks containing high saturated fat like coconut oil, butter and animal fat etc. may increase blood cholesterol level, therefore, it is discouraged to eat those high fat snacks. include cookies, wafer biscuits, cakes, egg tart etc.; oily deep-fried snacks include deep-fried chicken wing and French fries.
2. Cut down high sugar content snacks
Sugar increases the energy of foods. Choosing snacks with lower sugar content would reduce caloric intake and play an important role in body weight management. High sugar content snacks include dessert soup, cakes, chocolate, soft and nicotine ed juice.
3. Avoid high sodium snacks
Eating high sodium foods over a period of time may increase blood pressure, so choose more often snacks with lower sodium content, and avoid choosing snacks added with salty seasonings and containing preserved meat. , luncheon meat, nuts added with salt and preserved plum etc.
4. Choose more often high fiber snacks
Dietary fiber has different functions in our body; it would benefit overweight people as it gives the sense of satisfaction, and in turn lower their food intakes. Dietary fiber would also benefit people with hypercholesterolemia because of its possible lipid Apart lowering from this, fiber helps to relieve constipation and to lower the incidence of certain types of intestinal diseases.
Examples of high fiber snacks include all kinds of fruits like apple, banana, orange, cherry tomato, oatmeal, wholemeal bread, whole wheat biscuit, and beans like red bean or kidney bean etc.
5. Have appropriate portions of snacks and snack time
Portion sizes of snacks should be appropriate and not in excess. Snack time can be arranged between two main meals in order not to affect the appetite. It is discouraged to have snacks just before going to bed; otherwise indigestion and weight gain may be resulted.
Vocabulary
nutritious[nju: "tri??s] adj. Nutritious, nourishing
minimize["minimaiz] v. to reduce, to despise extremely;

adj. Minimized, to achieve the minimum
saturated ["s? t?? reitid] adj. saturated, dark color;

v. To infiltrate, to saturate (past tense of saturate)

Biscuits ["biskits] n. biscuits, small bread (plural form of biscuit)
dietary ["dai?t?ri] n. prescribed food, dietary regulations;
adj. diet, meals

(End of this chapter)