单选题   The argument between the two patients became so fierce that the doctor had to ______.
 
【正确答案】 D
【答案解析】 题干：两位患者的争吵很激烈，医生不得不出面干涉。alleviate减轻，缓和(痛苦或困难)：aggravate使加重，使恶化；extinguish熄灭(火或光)，使消亡，使(想法或希望)破灭；intervene干预，介入。