1. prevent vt.预防; 阻止
例句:Atmospheric conditions often prevent observation of stars.
大气的情况常使人们无法观察星星。
2. appear vi.发表; 出现,显现
例句:I have to appear in court on a charge of drunken driving.
我被控告醉酒驾驶而要出庭受审。
3. urgency n.紧迫; 急迫; 急事
例句:In case of urgency, call the police.
一旦发生紧急情况, 打电话给警察。
4. protect vt.保护,保卫
例句:Game laws protect wild life.
狩猎法保护野生动物。