Zài / “tā / yīng / gāi / huí / jiā” / zhè / jù / huà / lǐ / “yīng / gāi” / shì / zhù / dòng / cí

在“他应该回家”这句话里，“应该”是助动词。

In the sentence “He should go home,” “应该” is an auxiliary verb.