A、Its location for viewing in the world B、its timing on the calendar. C、Its movement across the sky. D、Its beautiful scene. B对于这

On December 25, 2000, many people across North America received a rare Christmas treat when the moon passed in front of the sun resulting in a partial solar eclipse.
   Solar eclipses occur when the moon passes between tile earth and the sun, and the moon’ s shadow covers part of the earth, and a total solar eclipse takes place when the moon’s shadow blocks out the sun entirely. What made this particular solar eclipse unique was that such an event has occured on December twenty - fifth only 30 times during the past 5000 years, the last time in 1954. But people must be exceptionally careful when attempting to view a solar eclipse. Without taking precautionary measures, one can permanently damage the retina of the eyes; however, there are several safe methods of witnessing this heavenly marvel.
   First, you can view a solar eclipse by using eclipse safety glasses for filtering out the sun’ s harmful rays. They should be used when any part of the sun is visible. Sunglasses can block out some of the sun’s ultraviolet rays, but the results can be very deceptive. The eye’ s natural reaction to this darken state when wearing sunglasses is to make the pupil larger, which allows in more light and can intensify the damage to your eyes. u can also watch an eclipse by projecting the sun’ s image on a piece of paper either by using a telescope, or easier yet, by creating a pinhole in a piece of paper and viewing the result on another piece of paper, thus called a pinhole projector.
   Only during a total eclipse when the sun is completely and briefly covered can you watch the eclipse without eye protection. Even then, extreme caution should be taken. In case you didn’t catch this last spectacular eclipse on December twenty - fifth, 2000, there ’ s no need to fret. Your posterity can record the next eclipse on Christmas in the year 2307, but only if their visiting the west coast of Africa for the holidays.