相关单词近义词 compulsory 强制的, essential 本质的, necessary 必要的, vital 至关重要的, forced 被迫的, forcible 强制的, indispensable 不可缺少的, mandatory 法定的, requisite 必要的, obligatory 强制性的, prerequisite 先决条件, needful 必需的, needed 需要的反义词elective, 选举的临近词require, required time, required flow, required area, required list, required NPSH, require nerve, required over, require study, Required Date, required book 返回 required