某种钢材焊接时高温出现了结晶裂纹，裂纹具有氧化色彩，试分析该裂纹产生机理以及防治措施
下列属于国际金融市场的发展特点的有（） ["金融区域化","金融自由化","金融证券化","金融创新化"]
胶带内钢条折断和胶带面破损的原因有哪些？
16Mn母材中含有较高的S，P时，应如何保证焊缝的韧性
Refer to the exhibit. In the diagram, the switches are running IEEE 802.1s MST. Which ports are in the MST blocking state?（） ["GE-1\/2 and GE 2\/1","GE-1\/1 and GE-2\/2","GE-3\/2 and GE 4\/1","no ports are in the blocking state","There is not enough information to determine which ports are in the blocking state"]
氮的溶解形式及对焊接质量的影响？
