移动电具的绝缘电阻应不低于()
A.0.5MΩ
B.1MΩ
C.2MΩ
D.10MΩ
A.0.5MΩ
B.1MΩ
C.2MΩ
D.10MΩ
B、户外使用其专用控制配电盘应置于具有防水、防雨功能的配电箱内
C、I类工具电源线必须使用橡胶电缆,单相用三芯电缆、三相用四芯电缆、电缆绝缘层应无破损、龟裂、电缆中间无接头
D、操作手柄装有应有良好的绝缘物,在潮湿的条件下作业时,操作者必须穿绝缘鞋、戴绝缘手套。构架上操作开关应灵敏、可靠、安装要牢固
B.移动式电气设备的保护零线不应单独敷设,应采用带有保护心线的橡皮套软线作为电源线
C.在潮湿或金属构架上等导电性能良好的作业场所,应使用Ⅰ类设备
D.在锅炉内、金属容器内、管道内等狭窄的特别危险场所,应使用Ⅱ类设备
E.绝缘电阻合格,带电部分与可触及导体之间的绝缘电阻Ⅱ类设备不低于7MΩ
A. 电气工具分为I、Ⅱ、Ⅲ类
B. I类工具时需要进行保护接地或保护接零的附加安全措施
C. Ⅱ类工具需要采用接地或接零保护
D. Ⅲ类工具由独立电源或具备双线圈的变压器供电
B.一般场所,手持电动工具应采用Ⅱ类设备
C.Ⅱ类设备带电部分与可触及导体之间的绝缘电阻不低于2MΩ
D.在潮湿或金属构架等导电性能良好的作业场所,应使用Ⅱ类或Ⅲ类设备
B.一般场所,手持电动工具应采用Ⅱ类设备
C.Ⅱ类设备带电部分与可触及导体之间的绝缘电阻不低于2M
D.在潮湿或金属构架等导电性能好的作业场所,应使用Ⅱ类或Ⅲ类设备
B.But an international team of researchers, including Dr. Richmond from GW’s Columbian College of Arts and Sciences,have discovered that human walking upright, may have originated millions of years ago as an adaptation to carrying scarce,high- quality resources.
C.Here,35 percent of the chimpanzees activity involved some sort of bipedal movement, and once again, this behavior. appeared to be linked to a clear attempt to carry as much as possible at one time
D.XXXXXX
E.Researchers allowed the wild chimpanzees access to different combinations of two different types of nut — the oil palm nut,which is naturally widely available,and the coula nut, which is not.
F.The chimpanzees regarded the coula nuts as a more highly-prized resource and competed for them more intensely
B.Try however hard you may
C.However hard you may try
D.Try hard however you may
为了保护您的账号安全,请在“简答题”公众号进行验证,点击“官网服务”-“账号验证”后输入验证码“”完成验证,验证成功后方可继续查看答案!