南阳中学有语文教师8名、数学教师7名、英语教师5名和体育教师2名。现要从以上四科教师中各选出1名教师去参加培训,问共有几种不同的选法?( )
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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