单项选择题

Questions 18 to 20 are based on the following passage. At the end of the passage, you will be given 15 seconds to answer the questions. Now listen to the passage. Why do astronomers often use photographic plates

A．To decrease the time it takes to photograph objects.
B．To avoid using a telescope.
C．To sharpen the color of what they observe.
D．To obtain images of distant objects.

<上一题目录下一题>

热门试题

单项选择题

Why did the woman have to stop playing in the volleyball game

A．She had to go home.
B．She was too tired to continue.
C．She had to finish her schoolwork.
D．She was thirsty.

单项选择题

How did people in the early Ice Age keep warm

A．They lived in large groups.
B．They used sand as insulation.
C．They kept fires burning constantly.
D．They faced their homes toward the south.

Questions 18 to 20 are based on the following passage. At the end of the passage, you will be given 15 seconds to answer the questions. Now listen to the passage. Why do astronomers often use photographic plates 您的浏览器不支持 audio 元素。

Questions 18 to 20 are based on the following passage. At the end of the passage, you will be given 15 seconds to answer the questions. Now listen to the passage. Why do astronomers often use photographic plates