对于国产微机型距离保护,如果定值整定为Ⅰ、Ⅱ段经振荡闭锁,Ⅲ段不经 振荡闭锁,则当在I段保护范围内发生单相故障,且0.3s之后,发展成三相故障,此时将由距离保护()切除故障。
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The reason why he didn’t come to school was ill.
A. due to
B. that he fell
C. because he fell
D. because of falling
采用分区防水的区段,注浆顺序为先进行()、再进行背贴止水带上花软管注浆、最后进行()。
He has been to Beijing. _________.
A. So have I
B. So am I
C. Neither have I
D. Neither am I
高处作业是指在坠落高度基准面()以上(含2m),有可能坠落的作业处进行的作业。高处作业可分为临边作业、洞口作业、悬空作业三大类。
A. 2m
B. 3m
C. 4 m
D. 5m