A．UntilB．UnlessC．OnceD．However
A. Until
B. Unless
C. Once
D. However
查看答案
A．factB．occasionC．caseD．truth
A. fact
B. occasion
C. case
D. truth
A．frankB．hard-workingC．politeD．reserved
A. frank
B. hard-working
C. polite
D. reserved
Which of the following statements is NOT related to light pollution？
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.
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 m study stars.
D. No. Because faint light given off by stars can still be seen on a clear night.
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