• 突然进入

suddennessn.意外；突然suddenadj.突然的；出乎意料的n.突发之事Sudden pity teared his sight.一股油然而生的怜悯之情使他眼泪汪汪。sudden unexpected natural death猝死Sudden Death Syndrome in cattle牛猝死症sudden onset of precordial pain卒心痛sudden death syndrome of soybean大豆猝死综合症sudden neurosensory hearing loss猝发性神经感觉性听力障碍sudden public healty emergencies突发公共卫生事件sudden unexpained death syndrome不明原因瘁死综合症sudden unexpected death of infant婴儿意外猝死Sudden sensorineural heating loss突发性聋

1. The children were surprised by the sudden entry of their teacher.
   老师突然进来把孩子们吓了一跳。