把这篇文章命制成标准的20题完形填空Many people are aware of the beauty of a solar eclipse but are surprised to learn that lunar eclipses are often just as impressive While total solar eclipse lasts only for a few minu

What is surprising to many people about lunar eclipses?
How long can a total lunar eclipse last?
What is the opinion of both amateur and professional photographers about lunar eclipses?
When do lunar eclipses occur?
What causes a lunar eclipse?
What factors determine the type of lunar eclipse that occurs?
What is a penumbral eclipse and is it easily observed?
What is the difference between total and partial eclipses and how are they observed?
Are lunar eclipses safe to watch?
What is eclipse blindness?
How can a solar eclipse be safely viewed?
Is special equipment necessary to view a lunar eclipse?
What can help a viewer appreciate the beauty of a lunar eclipse?
What kind of radiation can cause burns of one's eyes?
What is the only way to safely view a solar eclipse?
Is the Moon's light safe to watch?
What is the phenomenon that is completely safe to watch?
What is the main advantage of lunar eclipses over solar eclipses?
How many times do lunar eclipses occur in a year?
What is the most popular type of lunar eclipse among photographers