练习：
1. When can people see 14,000 stars?
A) When they have a fairly good telescope.
B) When they are in a large city.
C) When the night sky is clear of clouds, moonlight and artificial lights.
D) When the night sky is without haze and fog.
2. Which of the following statements is NOT related to light pollution?
A) A haze of light is formed from artificial lights such as streetlights and building lights.
B) Lights from different sources in the city stream into space and illuminate the night sky.
C) The night sky is illuminated by the lights from big glowing cities in the night.
D) Stargazing becomes difficult because there is a layer of haze in the air.
3. Does the writer think growing cities affect astronomers' work? Why does he think so?
A) Yes. Because the once dark rural areas are polluted by lights.
B) No. Because they can still see stars in rural areas.
C) Yes. Because rural areas are not a good place for astronomers to study stars.
D) No. Because faint light given off by stars can still be seen on a clear night.
4. How does light pollution affect wildlife? Which of the following is NOT correct?
A) Animals may go off course due to the attraction of artificial lights.
B) Animals might be attracted by artificial lights to go into cities.
C) Artificial lights at night may make migrating birds lose their way.
D) Attracted by artificial lights, birds fly into lighted buildings.
5. Which of the following is closest in meaning to the title "Light Night, Dark Stars"?
A) The night sky is light colored and stars are black.
B) Lights appear at night and stars are seen in the dark.
C) City lights illuminate the night sky and make rs invisible.
D) City lights at night illuminate stars in the sky.
