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Have you ever looked toward the sky on a fall day and witnessed a group of migrating birds? If so, you probably noted the V-shaped formation of the birds or the birds flying in a ball-like formation. Why do birds fly this way? Many theories have been developed to explain the formation patterns of different types of birds.
One theory is that birds fly in certain formations to take advantage of the laws of nature. The birds know that flying in a V-shaped pattern will save energy. Like the lead cyclist in a race who decreases wind force for the cyclists who follow, the lead bird cuts wind force for the birds that follow. This decrease in wind force means that the birds use up to 70 percent less energy during their flight. When the lead bird becomes tired, a more rested bird takes over that position.
But saving energy is important for more than one reason. Sometimes food is short during migration flights. Keeping energy enables the birds to fly longer distances between meals.
When food is sighted, the birds guide one another in a different way. When a bird identifies a familiar feeding area, it might turn around in order to signal the group to change direction. Then, this bird becomes the new leader. It helps guarantee that other birds will know exactly where it is going. Then the whole group makes a change in direction, gently streaming from the sky down to the ground. This formation is like an arrow pointing to the location of food.
Scientists have also studied the birds that sometimes fly in a ball-like formation. Researchers believe that the birds come together if a predator（天敌） is spotted. The predator may then become impatient waiting for a single bird to fly away from the group. The birds will often dip and dive as a group, frustrating even the most persistent enemy. Scientists report that this is a very effective method of defense against an attack.
The birds care for their fellow fliers through teamwork. As transportation expert Henry Ford once said, “If everyone is moving forward together, then success takes care of itself.” When it comes to teamwork, these feathered fliers are a soaring success!
63. According to the passage, we can learn that birds ___________.
A. move faster than cyclists
B. prefer to fly in a V formation
C. are smarter than other animals
D. play different roles in a formation
64. When food is sighted, ____________.
A. the group follows the discoverer
B. the lead bird decides what to do
C. the discoverer leaves the group
D. the whole group forms a stream
65. To protect themselves from attack, birds will _____________ .
A. break into groups B. come close together
C. change directions D. fly up and down
66. Which is the best title for the passage?
A. A Bird’s-Eye View of Teamwork.
B. Success Takes Care of Itself.
C. The Strongest Will Survive.
D. A Science Behind Flying.
D
A Myth
It is true that world population is growing, but this is not the cause of our current and future global problems. Believing this will cause us to ignore the real problem and risk long-term damage to our planet.
Let me start by explaining why overpopulation is a myth. For one thing, the UN Population Division regularly predicts population growth but provides a low variant (变量), medium variant, and high variant to factor in various possibilities. In the 2010 revision, their high variant suggests that the world population will be almost 16 billion in 2100, but the low variant predicts it will peak at 8 billion and decrease to just over 6 billion by 2100. In most cases, it is the low variant that has come true in the past, suggesting the same will be true of their future population predictions. In addition to this, the size of families is actually decreasing.
For another, if the Earth is overpopulated, there needs to be insufficient (短缺) food, water, and space for humans to live. However, Indian economist Raj Krishna estimates that India alone is able to increase crop produce to the point of providing the entire world’s food supply. The World Food Programme confirms that there is sufficient food grown to feed the world and there is the same amount of fresh water on the planet now as there was 10,000 years ago. So how is it possible that the number of people in the world is affecting our planet?
Therefore, it is not an increase in population but an increase in consumption that is a severe threat. Materialism and overconsumption are facts of life for everybody in the western world, as possessions reflect a person’s status in society and people strive to obtain happiness through owning the latest fashionable goods. Not only that, but waste is a common occurrence which has a huge effect on our resources. It is a sad truth that 80% of the world’s resources are currently used by just 20% of the world’s population.
Our overconsumption must be addressed now to make our lives more sustainable (可持续的) and avoid continuing the terrible damage to the environment we are causing. The key is education. If we do not work towards this but instead focus on the wrong issue, we may find ourselves living on a planet that can no longer sustain human life.
67. According to the author, what causes our current and future global problems?
A. The increase in population.
B. Shortage of food and water.
C. The fast growth of material needs.
D. Failure to protect the environment.
68. The underlined word “myth” in Paragraph 2 is closest in meaning to _________.
A. fact B. misconception C. possibility D. uncertainty
69. The author stresses that _____.
A. people should save food and water
B. economists are making wrong predictions
C. wrong judgment leads to serious consequences
D. measures should be taken to reduce population
70. What is mainly discussed in the passage?
A. The real cause of global problems.
B. The severe effect of overpopulation.
C. Reasonable use of natural resources.
D. Methods to reduce overconsumption.
