Halloween’s origins date to the ancient Celtic festival __1__
of Samhain(pronounced sow-in). The Celts, which lived __2__
2,000 years ago in the area that is now Ireland, the United Kingdom,
and northern France, celebrated its new year on November 1.
This day marked the end of the summer and the harvest and __3__
the beginning of the dark, cold winter, a time of year that was
often associated with human death. Celts believed that at the __4__
night before the new year, the boundary between the worlds
of the live and the dead became blurred. On the night of October __5__
31, they celebrated Samhain, when it believed that the ghosts __6__
of the dead returned to earth. In addiction to causing trouble and
damaging crops, Celts thought that the presence of the
other worldly spirits made it easier for the Druids, or Celtic Priest,
make predictions about the future. For a people entirely dependent __7__
on the volatile natural world, these prophecies were an important
source of comfort and direction during the long, dark winter.
To commemorate the event, Druids built huge sacred bonfires,
Which the people gathered to burn crops and animals as sacrifices __8__
to the Celtic deities. During the celebration, the Celts wore
costumes, typically consisted of animal heads and skins, and __9__
attempted to assume each other’s fortunes. When the celebration __10__
was over, they re-lit their hearth fires, which they had extinguished
earlier that evening, from the sacred bonfire to help protect them
during the coming winter.

答案：
1.^to—back date back to 固定搭配，意为“追溯至”。
2.which—who Celts 是“盖尔特人”的意思，应该用who来引导非限制性定语从句。
3. the summer-- / summer 季节前面不用加冠词。
4.at—on 在某个特定日子的晚上用介词on。
5.live—living the living 表示“活着的人”与the dead “死者”相对。
6.^ believed—was 这里应该用被动句。
7.^ make—to 动词不定式短语做真正的宾语。
8.which—where 或者^which—around 先行词bonfire在这里是表示地点的名词。
9.consisted—consisting 用现在分词表示主动。
10.assume—sell “算命”英语用“tell one’s fortune”.