不测事件；偶然性；非常时期的英文

• eventuality

• 不测:    accident; mishap; contingenc ...
• 事件:    event; incident
• 偶然性:    contingency; fortuity; chanc ...
• 非常时期:    an extraordinary period
• 不测事件:    accident; calamity; contingency; eventuality; mishap; unexpected event