焊割作业前必须按规定办理“三级动火”手续。进行焊割作业时,必须配备灭火器材,并指派监护人员。( )
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实施房屋简单维修时,只要高度注意安全,不带安全帽和没有系安全带也可以登高作业。( )
A. 对
B. 错
灭火的基本原理可以归纳为:冷却法、窒息法、隔离法和化学抑制法。()
A. 对
B. 错
Choose the best answer to complete each sentence.1. I want to help him, ________ I'm not sure I know how.
A. because
B. but
C. so
Choose the best answer to complete each sentence.The picnic this weekend has been cancelled _________ bad weather.
A. due to
B. but
C. because