【单选题】52碳素钢的质量分类是按下列哪一条进行分类的?( )
【单选题】按合金元素总含量进行分类时,低合金钢的合金含量为()。
【多选题】钢的主要元素除铁、碳外,还有硅、锰、硫等,按合金含量进行分类包括()。
【简答题】新民主主义革命的动力有哪些?新民主主义革命的对象是?
【简答题】阅读理解。 Last week, Richard's wife Leila had an accident. Richard's youngest child, John, was at home when it happened. He was playing with his new toy car. Richard had given it to him a week before, for...
【多选题】中国由旧民主主义革命向新民主主义革命的转变和由新民主主义革命向社会主义革命的转变的共同之处有( )