The mothers waited outside the primary school for their children to come out. One by one, the children appeared until only one woman was left standing there. She began to look worried and took out her mobile phone. Suddenly, a small boy came running out of the school towards her. As he reached her, she scooped him up and carried him to her car.

Although most areas of Egypt are quite dry, there are a lot of crops grown in the Nile valley. This would not be possible without the help of the river. Farmers dig canals which carry water from the river for the irrigation of their crops.

irrigation means:

The first airplanes were not able to fly at a great altitude. As more modern aircraft have been developed, however, it has become common for airline passengers to travel at more than 30,000 feet, while some military aircraft have reached more than 60,000 feet.

altitude means:

Many of the cities in the poorer parts of the world don’t smell very nice, particularly when the weather gets hot. The reason for this is simple: the population has grown so much that the waste removal system is unable to remove the large quantities of sewage that is produced by so many people living in such crowded conditions.

sewage means:

The students were studying chemistry in the laboratory. They were interested in discovering the effect of heat on different chemicals. Ali put his chemical in a vessel and held it over the flame. Suddenly, the container cracked, and the chemical spilled all over the workbench.

vessel means:

Ahmed has recently had to spend a lot of money to have his car fixed. One of the pistons did not fit tightly enough inside the cylinder. The results of this were that the car was losing power and the engine was vibrating. The car was also burning a lot of oil. Ahmed had to add extra oil every few hundred kilometers.

pistons means

Sami needs to buy a new vacuum cleaner. The one he has now is old, and it doesn’t do a very good job. Sometimes he thinks that it just blows the dust around rather than sucking it up. When he checks the bag inside, he finds very little dust there. He wants a vacuum cleaner with more suction so that he can clean his apartment effectively.

suction means:

The Air Quality Index (AQI) is a standard indicator of the air quality in a location. AQI measures mainly ground-level ozone and small particles of solids in the air. We call these “aerosols.” Some occur naturally, caused by dust storms and vegetation, but a lot are caused by man. The main cause of man-made pollution is the large amount of harmful material discharged by motor vehicles. This is made worse by the discharge from industries, particularly those burning fossil fuels.

discharged means:

Have you ever been a front-seat passenger in a car traveling very fast around a left-hand curve in the road? Think what happens to your body. Your body is forced towards the outer edge of the car and then pushes against the door. You are experiencing centrifugal force. You are being forced away from the center of the bend.

centrifugal means:

Yesterday, Waleed cooked some eggs for breakfast. When the eggs were ready, he took the pan off the stove to carry it to the kitchen table. As he turned towards the table, he slipped on some grease on the floor and dropped the pan. When the pan hit the floor, the eggs slid out and went under the refrigerator. Waleed was so angry that he picked up a plate and flung it across the room, where it broke into small pieces.

flung means:

Pumps are produced for many different uses. Their basic function is to force liquids to move from one place to another. The most common type of pump, however, is not man-made. It is the human heart, which circulates blood through the arteries to all parts of the body.

We know that the earliest type of pump was the Archimedes’ screw. It was named after the famous Greek mathematician and engineer who described it over 2,000 years ago, but it is doubtful that he invented it. It is now believed that it was used at least 400 years earlier in the time of King Sennacherib of Assyria. This type of pump scoops up water at the bottom end and raises it to the top by rotating the screw. The screw is turned either by hand or by wind power. The Archimedes’ screw is still widely used in many countries for raising water from wells and for irrigation.

Vehicles have pumps to force gasoline out of the gasoline tank into the carburetor. Vehicles with water-cooling systems also have pumps to circulate water around their engines.At the gasoline station, a pump is operated to fill the tank in your car. Power pumps are installed on fire engines to force water or chemicals to high altitudes. Pumps are also used in water supply systems, air conditioning systems, refrigeration (where a pump is usually called a compressor), the movement of sewage, flood control, and various marine services.

Pumps are designed in different shapes and sizes according to the job they have to do. They also vary a lot in their capacity. The type of pump chosen for a particular job is determined by the pump capacity as well as by the density of liquid to be pumped. Pumps may get their power from internal combustion engines or electric motors, or they may be operated manually. Wind power is commonly used for irrigation. Solar power is increasingly used to provide power for electric motors in remote locations.

Today, there are many different types of pumps used in the oil industry. Some pumps force crude oil and other products from one processing vessel to another. Others push the crude oil for hundreds of kilometers through pipelines or from storage tanks onto tankers. Reciprocating pumps and centrifugal pumps are two of the pumps widely used in oil processing plants. In a reciprocating pump—one that moves backwards and forwards—the reciprocating part is the piston. The piston is attached to a rod or shaft. The shaft moves back and forth, or up and down, inside a cylinder. On the cylinder, there are two valves. One valve allows the liquid to enter the cylinder when suction is taking place and the piston is moving outward. When the cylinder is filled with liquid, the inlet, or suction, valve closes. When discharge occurs, the outlet valve opens, and the piston moves forward, forcing the liquid out of the cylinder.

The centrifugal pump operates on the principle of centrifugal force. This is a circular force which tends to push a substance away from the center of a circle. In this kind of pump, the liquid enters through a suction inlet at the center of the pump and hits a number of fast-rotating blades. The centrifugal force caused by the rotating blades flings the liquid outward, and it is pushed out through the discharge outlet.

The only natural pump mentioned in the article is the _____.

We know that the earliest type of pump was the Archimedes’ screw. It was named after the famous Greek mathematician and engineer who described it over 2,000 years ago, but it is doubtful that he invented it. It is now believed that it was used at least 400 years earlier in the time of King Sennacherib of Assyria. This type of pump scoops up water at the bottom end and raises it to the top by rotating the screw. The screw is turned either by hand or by wind power. The Archimedes’ screw is still widely used in many countries for raising water from wells and for irrigation.

According to the article, the Archimedes’ screw _____.

We know that the earliest type of pump was the Archimedes’ screw. It was named after the famous Greek mathematician and engineer who described it over 2,000 years ago, but it is doubtful that he invented it. It is now believed that it was used at least 400 years earlier in the time of King Sennacherib of Assyria. This type of pump scoops up water at the bottom end and raises it to the top by rotating the screw. The screw is turned either by hand or by wind power. The Archimedes’ screw is still widely used in many countries for raising water from wells and for irrigation.

The underlined word “it” in paragraph 2 refers to _____.

Pumps are also used in water supply systems, air conditioning systems, refrigeration (where a pump is usually called a compressor), the movement of sewage, flood control, and various marine services.

According to the article, refrigeration pumps are _____.

You can infer from the article that a dense liquid _____.

Pumps are designed in different shapes and sizes according to the job they have to do. They also vary a lot in their capacity. The type of pump chosen for a particular job is determined by the pump capacity as well as by the density of liquid to be pumped.

According to the article, the design of a pump depends a lot on _____.

Some pumps force crude oil and other products from one processing vessel to another. Others push the crude oil for hundreds of kilometers through pipelines or from storage tanks onto tankers. Reciprocating pumps and centrifugal pumps are two of the pumps widely used in oil processing plants. In a reciprocating pump—one that moves backwards and forwards—the reciprocating part is the piston.

Both reciprocating pumps and centrifugal pumps _____.