在金属结构中或容器内操作时，安全照明灯的电压为36V。()
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The phrase "a small step for mankind" (Para. 5) shows that the increased endowment spending will
A. encourage more public spending
B. contribute to social development
C. harmonize different schools
D. pave the way for free education
在潮湿环境操作时，只要戴好绝缘手套和穿好绝缘鞋就可以保证安全。()
The statement "Narcissus met a nasty end" (Para. 2) implies that _____.
A. selfishness of a boss will be subject to public criticism
B. egotism of chief executives may lead to undesirable consequences
C. a self-centered boss is always troubled with business disasters
D. boss-worship will result in self-asserted leaders
臭氧是一种淡蓝色的有毒气体，具有刺激性气味。明弧焊可产生臭氧，氩弧焊和等离子弧焊更为突出。臭氧浓度与焊接材料、焊接规范、保护气体等有关。()
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