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 (47) between the 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 (48) . What made this particular solar eclipse unique was that this event has occurred on December twenty-filth only 30 times (49) the past 5000 years, the last time in 1954.
But people must be exceptionally (50) when attempting to view a solar eclipse. Without taking precautionary (51) , one can permanently damage the retina of the eye; however, there are several safe methods of (52) this heavenly marvel.
First, you can view a solar eclipse by using eclipse safety glasses for filtering out the sun’s (53) 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 (54) to this darkened state when wearing sunglasses is to make the pupil larger, which allows in more light and can (55) the damage to your eye.
You can watch an eclipse by projecting the sun’s (56) 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.
[A] lively [I] during
[B] passes [J] intensify
[C] among [K] measures
[D] careful [L] reaction
[E] target [M] investigating
[F] entirely[N] harmful
[G] image [O] poses
[H] witnessing
参考答案：I
解析：该空格后为表示时间的名词短语the past 5000 years，因此空格处应选可以引导时间状语的介词。原句意为“这种情况______过去五千年在12月25日只出现过30次”，因此所选介词应表示“在……(时间)之间”，I(在……期间)最适合。