词形与变位助动词essere过去分词accaduto副动词accadendo直陈式现在时accado, accadi, accade, accadiamo, accadete, accadono未完成过去时accadevo, accadevi, accadeva, accadevamo, accadevate, accadevano简单将来时accadrò, accadrai, accadrà, accadremo, accadrete, accadranno条件式现在时accadrei, accadresti, accadrebbe, accadremmo, accadreste, accadrebbero虚拟式现在时accada, accada, accada, accadiamo, accadiate, accadano命令式通常不用命令式