【单选题】钢材的时效强化是指经一定处理后,钢材的( )会随时间的延长而逐渐提高的现象。
【判断题】凡经过整车大修、总成大修、二级维护后竣工出厂的车辆,在维修竣工验收合格后,必须由承修方签发《汽车维修竣工出厂合格证》,并向托修方提供相应的维修技术资料
【判断题】沉淀淬硬钢是一种高抗拉强度钢,它通过形成碳氮化铌沉淀物来提高钢材的强度。()
【简答题】O. Henry was a pen name used by an American writer of short stories. His real name was william Sydney Porter. He was bom in North Carolina in 1862. As a young boy he lived an exciting life. He did not...
【多选题】钢材的化学成分中,对提高钢材强度有帮助的是( )。
【简答题】People think that writing short stories is easy because they are short. But in fact they are hard to write well. There are only a few writers of good short stories and the American writer O. Henry is ...