On september 11 this year , the twin towers of the world trade center in new york city completely collapsed just over one hour after fires raged in them upon the crash of two aeroplanes into them . it was reported that one of the causes of their collapse was the severe weakening of the load - bearing strength of the towers steel - based load - bearing structure under extreme heat 本年九月十一日,纽约世界贸易中心两幢大楼遭飞机撞击后燃烧一个多小时即完全倒塌,据报原因之一是该两幢建筑物的主要承力结构材料是钢铁,而钢铁的承重能力会在高温下大幅下降。
On september 11 this year , the twin towers of the world trade center in new york city completely collapsed just over one hour after fires raged in them upon the crash of two aeroplanes into them . it was reported that one of the causes of their collapse was the severe weakening of the load - bearing strength of the towers steel - based load - bearing structure under extreme heat 本年九月十一日,纽约世界贸易中心两幢大楼遭飞机撞击后燃烧一个多小时即完全倒塌,据报原因之一是该两幢建筑物的主要承力结构材料是钢铁,而钢铁的承重能力会在高温下大幅下降。
Madam president , on 11 september this year , the twin towers of the world trade center in new york city completely collapsed just over one hour after fires raged in them upon the crash of two aeroplanes into them . it was reported that one of the causes of their collapse was the severe weakening of the load - bearing strength of the towers steel - based load - bearing structure under extreme heat 主席,本年9月11日,纽约世界贸易中心两幢大楼遭飞机撞击后燃烧一个多小时即完全倒塌,据报原因之一是该两幢建筑物的主要承力结构材料是钢铁,而钢铁的承重能力会在高温下大幅下降。