emergency: “紧急情况”，强调突如其来的事故或情况 crisis: “危机，危急”，着重某一事故或情况关系到生死存亡 urgency: “紧急，急迫（的状态）”，an emergency=a matter of urgency
economical: 节约的，节俭的。如：He is economical of money and time. economic: 经济(学)的。如：the economic doctrines of Ricardo(李嘉图的经济学说)