发电机排氢时要()进行,死角内氢气应排除干净。
参考答案:缓慢
The government has taken some measures to solve the shortage of electricity, but it may be some time
_________ the situation improves. [ ]
A. since
B. when
C. unless
D. before
有“高空王子”之称的美籍加拿大人科克伦,在毫无保护的情况下,手握10 m长的金属杆,在一根横跨在上海浦东两幢大楼之间,高110 m,长196 m的钢丝上稳步向前走,18min后走完全程,科克伦获得成功的过程充分地利用了哪些物理知识?(举两条)
(1)________________(2)________________