【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】固溶强化的作用是:不减弱钢的韧性,同时还提高了钢材的强度。
【单选题】We have learnt a lot from the ______.
A.
three month's training course
B.
three-month training course
C.
three-month-training course
D.
three months training course
【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】下表摘录了饮用天然矿泉水国家标准的部分内容: 项 目 锂 锶 锌 硒 溴化物 碘化物 硅 酸 溶解性 固体 指 标 (mg/L) ≥0.20 ≥0.20 ≥0.20 ≥0.01 ≥1.0 ≥0.20 ≥25.0 ≥1000 请分析表中信息,回答以下问题: (1)表中的锂、锶、锌、硒在这里是指______(填“元素”、“分子”或“原子”). (2)饮用天然矿泉水对人体健康有益,原因之一是矿泉水的p...