坐姿作业特点?
(1)不易疲劳,持续时间长;(2)身体稳定性好,操作精度高;(3)手脚可以并用作业;(4)脚蹬范围广,能正确操作。
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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