“红军不怕远征难,万里千山只等闲”指 。
长征
— Is that Jack speaking?
— Sorry, he isn't in right now. He _ the cinema with his aunt. [ ]
A. has been to
B. has gone to
C. have been to
D. have gone to
施工现场塔式起重机起重力矩限制器常见有()等安全隐患。
A、力矩限制器失效
B、力矩限制器调整不准确
C、力矩限制器行程开关未按规定设置
D、力矩限制器人为放大