某教师按快倒键把录音磁带倒到开始,按下暂停键,再同时按下放音键和录音键,准备好后释放暂停开始录音。可开头的几秒总没有录上,其原因最可能是( )
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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