The explosion of the challenger space shuttle and the Russian nuclear accident at chernobyl drive home the human quality of technology, they provide cases in which well-planned systems suddenly went haywire and there was no ready hand to set them right.

• 美国的宇宙飞船挑战者号的爆炸和俄罗斯切尔诺贝利核泄漏事故让我们理解了人类技术的脆弱面，在这两起事件提供的案例中,周密的计划突然陷入混乱，而有关当局却没有事先预备应急措施。