[名词解释] 单点电喷

直喷式 多点电喷 心包积液最突出的临床症状是（） ["干咳","吞咽困难","呼吸困难","胸痛","腹胀"] 对于就诊的每一个人都先介绍口腔的保健知识，属于（） ["一级预防","环境医学","二级预防","社会医学","三级预防"] 化油器 单点电喷