Solar energy is a long-lasting source of energy which can be used almost anywhere. To generate solar energy, we only need solar cells and the sun. Solar cells can easily be installed on house roofs, so no new space is needed and each user can quietly generate their own energy. Compared to other renewable sources, they also possess many advantages. Wind and water power rely on turbines which are noisy, expensive and easy to break down. Solar cells are totally silent and non-polluting. As they have no moving parts, they require little maintenance and have a long lifetime.

However, solar energy also has some disadvantages. We can only generate solar energy during the daytime because the system depends on sunlight. Besides, solar cells require a large area to work effectively. The main disadvantage of solar energy is that it costs about twice as much as traditional sources such as coal, oil, and gas. This is because solar cells are expensive. Scientists are hoping that the costs of solar cells will reduce as more and more people see the advantages of this environmentally friendly source of energy.

Solar energy is a long-lasting source of energy which can be used almost anywhere. To generate solar energy, we only need solar cells and the sun. Solar cells can easily be installed on house roofs, so no new space is needed and each user can quietly generate their own energy. Compared to other renewable sources, they also possess many advantages. Wind and water power rely on turbines which are noisy, expensive and easy to break down. Solar cells are totally silent and non-polluting. As they have no moving parts, they require little maintenance and have a long lifetime.

However, solar energy also has some disadvantages. We can only generate solar energy during the daytime because the system depends on sunlight. Besides, solar cells require a large area to work effectively. The main disadvantage of solar energy is that it costs about twice as much as traditional sources such as coal, oil, and gas. This is because solar cells are expensive. Scientists are hoping that the costs of solar cells will reduce as more and more people see the advantages of this environmentally friendly source of energy.

Solar energy is a long-lasting source of energy which can be used almost anywhere. To generate solar energy, we only need solar cells and the sun. Solar cells can easily be installed on house roofs, so no new space is needed and each user can quietly generate their own energy. Compared to other renewable sources, they also possess many advantages. Wind and water power rely on turbines which are noisy, expensive and easy to break down. Solar cells are totally silent and non-polluting. As they have no moving parts, they require little maintenance and have a long lifetime.

However, solar energy also has some disadvantages. We can only generate solar energy during the daytime because the system depends on sunlight. Besides, solar cells require a large area to work effectively. The main disadvantage of solar energy is that it costs about twice as much as traditional sources such as coal, oil, and gas. This is because solar cells are expensive. Scientists are hoping that the costs of solar cells will reduce as more and more people see the advantages of this environmentally friendly source of energy.

Solar energy is a long-lasting source of energy which can be used almost anywhere. To generate solar energy, we only need solar cells and the sun. Solar cells can easily be installed on house roofs, so no new space is needed and each user can quietly generate their own energy. Compared to other renewable sources, they also possess many advantages. Wind and water power rely on turbines which are noisy, expensive and easy to break down. Solar cells are totally silent and non-polluting. As they have no moving parts, they require little maintenance and have a long lifetime.

However, solar energy also has some disadvantages. We can only generate solar energy during the daytime because the system depends on sunlight. Besides, solar cells require a large area to work effectively. The main disadvantage of solar energy is that it costs about twice as much as traditional sources such as coal, oil, and gas. This is because solar cells are expensive. Scientists are hoping that the costs of solar cells will reduce as more and more people see the advantages of this environmentally friendly source of energy.

Solar energy is a long-lasting source of energy which can be used almost anywhere. To generate solar energy, we only need solar cells and the sun. Solar cells can easily be installed on house roofs, so no new space is needed and each user can quietly generate their own energy. Compared to other renewable sources, they also possess many advantages. Wind and water power rely on turbines which are noisy, expensive and easy to break down. Solar cells are totally silent and non-polluting. As they have no moving parts, they require little maintenance and have a long lifetime.

However, solar energy also has some disadvantages. We can only generate solar energy during the daytime because the system depends on sunlight. Besides, solar cells require a large area to work effectively. The main disadvantage of solar energy is that it costs about twice as much as traditional sources such as coal, oil, and gas. This is because solar cells are expensive. Scientists are hoping that the costs of solar cells will reduce as more and more people see the advantages of this environmentally friendly source of energy.

Air pollution, or dirty air, is (41)________ by many things. Great clouds of smoke come from factories chimneys. Cars send smoke and fumes into the air. Burning waste fills the air (42)_______ bits of dirt. Even burning leaves add smoke to the air. Smoke of all kinds is bad to breathe and can do great harm to the body. (43)_______ countries have made laws to limit the amount of fumes cars can exhaust into the air. They also set limits on pollution from power plants and factories. Although scientists have not yet been able to stop air pollution, they have found ways to make cars and factories burn fuel more cleanly. People are also more careful than they once were. For example, they have stopped burning fallen leaves in the (44) ______. We still have a long way to go. But if we all work together, we can (45) _________the problem.

Air pollution, or dirty air, is (41)________ by many things. Great clouds of smoke come from factories chimneys. Cars send smoke and fumes into the air. Burning waste fills the air (42)_______ bits of dirt. Even burning leaves add smoke to the air. Smoke of all kinds is bad to breathe and can do great harm to the body. (43)_______ countries have made laws to limit the amount of fumes cars can exhaust into the air. They also set limits on pollution from power plants and factories. Although scientists have not yet been able to stop air pollution, they have found ways to make cars and factories burn fuel more cleanly. People are also more careful than they once were. For example, they have stopped burning fallen leaves in the (44) ______. We still have a long way to go. But if we all work together, we can (45) _________the problem.

Air pollution, or dirty air, is (41)________ by many things. Great clouds of smoke come from factories chimneys. Cars send smoke and fumes into the air. Burning waste fills the air (42)_______ bits of dirt. Even burning leaves add smoke to the air. Smoke of all kinds is bad to breathe and can do great harm to the body. (43)_______ countries have made laws to limit the amount of fumes cars can exhaust into the air. They also set limits on pollution from power plants and factories. Although scientists have not yet been able to stop air pollution, they have found ways to make cars and factories burn fuel more cleanly. People are also more careful than they once were. For example, they have stopped burning fallen leaves in the (44) ______. We still have a long way to go. But if we all work together, we can (45) _________the problem.

Air pollution, or dirty air, is (41)________ by many things. Great clouds of smoke come from factories chimneys. Cars send smoke and fumes into the air. Burning waste fills the air (42)_______ bits of dirt. Even burning leaves add smoke to the air. Smoke of all kinds is bad to breathe and can do great harm to the body. (43)_______ countries have made laws to limit the amount of fumes cars can exhaust into the air. They also set limits on pollution from power plants and factories. Although scientists have not yet been able to stop air pollution, they have found ways to make cars and factories burn fuel more cleanly. People are also more careful than they once were. For example, they have stopped burning fallen leaves in the (44) ______. We still have a long way to go. But if we all work together, we can (45) _________the problem.

Air pollution, or dirty air, is (41)________ by many things. Great clouds of smoke come from factories chimneys. Cars send smoke and fumes into the air. Burning waste fills the air (42)_______ bits of dirt. Even burning leaves add smoke to the air. Smoke of all kinds is bad to breathe and can do great harm to the body. (43)_______ countries have made laws to limit the amount of fumes cars can exhaust into the air. They also set limits on pollution from power plants and factories. Although scientists have not yet been able to stop air pollution, they have found ways to make cars and factories burn fuel more cleanly. People are also more careful than they once were. For example, they have stopped burning fallen leaves in the (44) ______. We still have a long way to go. But if we all work together, we can (45) _________the problem.