q('4#3#We live at the bottom of an ocean of air that is about 20 miles deep. Because of its weight, the air above us exerts a force of about 15 pounds on every square inch of our bodies. On top of a high mountain the air above us weighs much less. Everest is the highest mountain on Earth.#The weight of air.'); q('4#0#The Antarctic is the coldest place on earth. In the colder regions of the world, the feathers of birds help retain their body warmth. On the other hand , the feathers of birds that live in the desert often serve to keep the external heat out. Because of this insulation, there are many kinds of birds that can sit in the desert heat all day and not be harmed by it.#The function of bird feathers.'); q('4#2#The internal temperature of our bodies is regulated very closely. For most people it is 37° Celsius when they are in good health. Temperature can also be measured in Fahrenheit. Sometimes, during an operation, surgeons will deliberately lower the body temperature of a patient in order to slow down body processes so that they can have more time to carry out the operation.#Body temperature.'); q('5#3#The surface of the earth is broken up into seven large plates that are about sixty miles thick. These continental plates float on a fluid layer of hot rock. They move with a speed of one to four inches per year. A garden snail can move at about 0.03 miles per second. On the other hand, lava from an erupting volcano can move as fast as sixty miles an hour.#The speed of geological processes.'); q('4#1#Since the second world war, life expectancy in areas where people are well-nourished has improved greatly. Vegetables are an important part of a healthy diet. For example, a newborn infant in Scandinavia can be expected to live more than eighty years. On the other hand, where diet and health conditions are not good, newborns may have a life expectancy as short as thirty years.#The influence of nutrition on life expectancy.'); q('4#3#It is likely that early in the history of the solar system the climate of Mars was very much like that of Earth as we know it today. It was warm enough for water to flow. Now it is so cold on Mars that carbon dioxide freezes at the Poles during the Martian winter. Frozen carbon dioxide is called "dry ice" and used in discos to produce smoke.#The climate on Mars.'); q('5#1#It\'s not true that cats have nine lives. The Ancient Egyptians thought cats were sacred animals. Cats have good memories, keen eyesight, and excellent senses of smell and hearing. These combine with their speed and agility to help them out of danger. So even though a cat may escape with its life many times, it still lives only once, just as any other animal.#The survival skills of cats.'); q('5#3#There are different stages in a butterfly\'s life. The first stage begins when the female lays her eggs on a plant which will provide food. Soon a caterpillar starts to form inside each egg. Not only insects lay eggs, but reptiles do too. After a few days or weeks the caterpillar will emerge as a butterfly.#Stages in the development of a butterfly.'); q('6#3#The bad-smelling odor of skunks is contained in a liquid which the animal produces. It discharges the liquid if it is frightened is in danger. The liquid is called musk. There is another animal named a musk ox, that lives in cold regions. Musk is produced by two glands at the base of the skunk\'s tail. It is squirted at any animal that tries to attack it.#How a skunk produces its foul smell.'); q('5#4#There are many characteristics that distinguish mammals from other types of animals. For example, mammals give birth to live young. They have a backbone and are warm-blooded. They have a well-developed brain and their bodies are covered with hair. All cats are mammals but not all mammals are cats.#The characteristics of mammals.'); q('5#4#Many fish that live in the middle or deepest parts of the ocean emit light. It is still not exactly understood what purpose this serves. It is believed that some fish emit light to signal to other fish. Others emit light from their undersides in order to disguise themselves so as to look like distant parts of the ocean. Light travels from the sun at a speed of more than 1,000 million kilometers per hour.#Why fish emit light.'); q('6#3#Grammar is an aspect of language about which learners have different opinions. Some learners are very interested in finding out or learning grammar rules and doing lots of grammar exercises. Others hate grammar and think it is the most boring part of learning a new language. English and German grammar have many similarities. Whatever opinion you have, however, you cannot escape from grammar. It is in every sentence you read or write, speak or hear.#Different opinions about learning grammar.');