Question

For humans, climbing Mount Qomolangma is seen as a great impressive achievement. People make movies, write books, and have essentially developed a whole industry surrounding the challenge that is this mountain. While we consider climbing the mountain as an athletic achievement, there is one animal, the bar-headed goose, does not think so.

As the species migrates (遷徙) from Central Asia to Southeast Asia every autumn, it must cross over the Himalayan range. These mountains force the bar-headed goose to fly at around 30,000 feet above sea level, which is the highest altitude for migratory birds.

These geese have special adaptions that allow them to survive at the altitude. For example, a special protein (蛋白質(zhì)) in blood cells that transports oxygen throughout the body allows their blood cells to combine with oxygen. Their circulatory system provides a constant supply of fresh, oxygenated blood to their wing muscles (肌肉). They have much larger lungs than other birds, which give them the ability to take in more air.

Scientists initially believe that the geese flow at an extremely high altitude for the full length of their migration. But later the data suggests that the birds use a much more effective way of travel. Instead of remaining at an extremely high altitude to fly over the mountain range, the geese hug the mountains, flying up and down depending on the obstacles (障礙物) in their way. This works better for them because they don’t have to use all their energy flying in an area with low oxygen; they can spend time flying at lower altitudes.

The geese also make use of nature to make this work easier. To fly down, they simply allow gravity to pull them. To fly back up, they make use of orographic (地形的) lift, which happens when flowing air meets an obstacle, such as a mountain. The mountain forces the air up, creating an upward draft. The birds take advantage of this draft, expending less of their own energy to fly up the mountain.

The way these birds have adapted to flying across the Asian continent during their annual migration is certainly an amazing way to see nature at work.

1.What does the underlined part "this work” in Paragraph 5 most probably refer to?

A. To fly down. B. To fly back up.

C. To fly over the mountain. D. To fly at lower altitudes.

2.How do the geese behave while crossing over the Himalayan range?

A. By flowing at an extremely high altitude all the way.

B. By taking advantage of the orographic lift.

C. By smoothing the obstacles in their way.

D. By forcing the air up, creating an upward draft.

3.What’s the main idea of this passage?

A. The geese’s amazing migration.

B. The highest flying record of geese.

C. The flying mystery of geese.

D. Mount Qomolangma and its geese.

Answer 1